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Report I
VOLUME I: MAIN REPORT
Biodiesel Manufacturing Processes
As part of Preparing Status Reports on Themes Related to
Technical and Scientific Utilization of Biofuel Utilization
Department of Science and Technology
Government of India
Submitted by
March 2012
Principal Investigator Somnath Bhattacharjee
Project Team
Shankar Haldar
Arvind Reddy
Nilanjan Ghose
Sharda Gautam
Aniruddha Bhattacharjee
Vineet Jain
Principal Advisor
Sudhir Singhal
AAcckknnoowwlleeddggeemmeenntt
Winrock International India (WII), New Delhi is thankful to the Department of Science and
Technology (DST) for awarding it the opportunity to work under the project entitled
“Preparing Status Reports on Themes Related to Technical and Scientific Aspects of Biofuels
Utilization”, and for extending its valuable support and co-operation during the assignment.
WII would like to extend a special word of gratitude to Prof. D.V. Singh and
Mr. Rajeev Sharma for their guidance and constant support during the preparation of this
report.
Grateful thanks to Ms. Meenakshi Gusain for carrying out the entire work of typing,
formatting and collating the report.
The authors thank Dr. Kinsuk Mitra, President, Winrock International India for his help in
successfully carrying out this study.
Special thanks are due to Mr. V.K. Kapoor, Formerly of the Indian Institute of Petroleum for
providing considerable help in finalising the contents of this report and very painstakingly
going through the final version including for editing it.
Winrock International India
New Delhi
Contents
Volume 1
Executive Summary i
Chapter 1: Introduction 1
1.1 Biodiesel 2
1.2 Project Deliverables 5
Chapter 2: Conversion to Biodiesel 6
2.1 Trans-esterification 7 2.1.1 Chemistry of trans-esterification process 9
2.2 Pyrolysis11 13
Chapter 3: Feedstock for Production of Biodiesel 16
3.1 Edible vegetable oils 17
3.2 Composition of Edible Vegetable Oils 18
3.3 Soybean Oil 19 3.3.1 Composition of Soybean Oil 19 3.3.2 Oil extraction from Soybean 20
3.4 Physical properties of Soybean Oil 20 3.4.1 Polymorphism 20 3.4.2 Density 21 3.4.3 Viscosity 21 3.4.4 Refractive index 22 3.4.5 Specific heat 22 3.4.6 Melting point 23 3.4.7 Heat of combustion 24 3.4.8 Smoke, flash and fire points 24 3.4.9 Solubility 25 3.4.10 Plasticity and ‘spreadability’ 25 3.4.11 Electrical resistivity 25
3.5 Oxidative Qualities of Soybean Oil 26
3.6 Palm Oil24 26 3.6.1 Composition and properties of Palm Oil 27
3.7 Canola/Rapeseed Oil24 27 3.7.1 Composition 28 3.7.2 Physical and Chemical properties of Canola Oil 29 3.7.3 Saponification number 29 3.7.4 Iodine Value 29
3.8 Sunflower Oil 30 3.8.1 Composition of Sunflower Oil 30
3.9 Sunflower oil refining 30
3.10 Physical refining process 31
3.11 Chemical refining process 32
3.13 Non-edible vegetable oils 37
3.14 Jatropha Oil 37
3.15 Waste cooking oil as biodiesel feedstock 38
3.16 Animal fats as biodiesel feedstock 39
3.17 Algae-based biofuels 39
Chapter 4: Conversion technologies to make Biodiesel 40
4.1 Trans-esterification of Triglycerides to Biodiesel 41
4.2 Novel highly integrated biodiesel production technology in a centrifugal contactor separator device 43
4.3 Biodiesel production process optimization and characterization to assess the suitability of the product for varied environmental conditions 44
4.4 Review on Activity of solid heterogeneous catalysts and nanocatalysts for biodiesel production 47
4.4.1 Solid Heterogeneous Catalysts 47 4.4.2 Heterogeneous Nanocatalytic Process for the Production of Biodiesel 50
4.5 A review on Biodiesel production through the use of different sources and characterization of oils and their esters as the substitute of diesel11 50
4.6 Process intensification technologies in continuous biodiesel production 51
4.7 A review on biodiesel production using catalyzed trans-esterification, reduction of undesirable FFA and refinement of biodiesel 52
4.8 One-pot process combining trans-esterification and selective hydrogenation for biodiesel production from starting material of high degree of unsaturation 55
4.9 Cheaper Ever Cat Fuels Process to Manufacture Biodiesel 55
4.10 Biodiesel production from acid oils and ethanol using a solid basic resin as catalyst 56
4.11 Supercritical biodiesel production, power cogeneration: Technical and economic feasibilities, 57
4.12 Biodiesel production unit 61
4.13 Process for the Conversion of Renewable Oils to Liquid Transportation Fuels 61
4.14 Improved and Innovative Process for the preparation of fatty acid methyl ester from triglyceride oil by trans-esterification using mechanically expelled oil from Jatropha Seeds 62
4.15 Reactive Distillation Methods and systems for alkyl ester production 63
4.16 Modified Reactor, Apparatus for Efficiency Improvements in Esterification and trans-esterification 64
4.17 Pyrolysis and Cracking for Biodisel Production11 65
4.18 Micro-emulsification 66
4.19 Summary 67
Chapter 5: Future Directions for Production of Biodiesel 70
5.1 Overcoming the shortcomings of trans-esterification processes 70 5.1.1 Static Mixers37 71 5.1.2 Micro-channel Reactors37 74 5.1.3 Oscillatory flow reactors37 74 5.1.4 Cavitational reactors37 76 5.1.5 Biodiesel Production Unit using cavitation pretreatment and cavitation
reactor43 77 5.1.6 Rotating/spinning tube reactors37 78 5.1.7 Esterification and trans-esterification systems, methods and apparatus47
79 5.1.8 Membrane reactors37 79 5.1.9 Centrifugal contactors37 79 5.1.10 Reactive Distillation 80 5.1.11 Method of Biodiesel Production 82 5.1.12 Heterogeneous catalysts, continuous process 82 5.1.13 Development of enzymatic catalysts 84
5.2 Noncatalyzed Trans-esterification 85 5.2.1 BIOX Process 85 5.2.2 Noncatalytic and Catalytic Supercritical process- One and Two Step
Approaches 85
5.3 Reactor and Process Design 88
5.4 Process Optimization 88
5.5 Continuous Processes 88
5.6 Development of one-pot process 88
5.7 Adsorbents for purification 89
5.8 Reactive Distillation 89
5.9 Biodiesel from Sludge 89
Chapter 6: Simulation & Modelling Activities for Biodiesel production 90
6.1 Simulation of the Reactive Distillation Process for Biodiesel Production 90
6.2 Excess Methanol Recovery in Biodiesel Production Process using a Distillation Column: A Simulation Study 91
6.3 Process Optimization for Biodiesel Production from Corn Oil and its Oxidative Stability 93
6.4 Economic Issues Related to Continuous Supercritical Biodiesel Production 95
6.5 Process Analysis and Optimization of Biodiesel Production from Vegetable Oils 95
6.6 Stochastic Modelling of Biodiesel Production Process 97 6.6.1 Problem Statement and Approach 97 6.6.2 Stochastic Modeling 97
Chapter 7: Biodiesel Units & Production Worldwide 99
7.1 Region 1: Asia 100 7.1.1 India 100 7.1.2 China 101 7.1.3 Malaysia 103 7.1.4 Indonesia 104
7.2 Region 2: Australia 105
7.3 Region 3: South America 106 7.3.1 Brazil 106 7.3.2 Argentina 109
7.3 Region 4: North America 110 7.3.1 Canada 110 7.3.2 United States 111
7.4 Region 5: Europe 112 7.4.1 European Union 112
Chapter 8: Economics For Biodiesel Production 115
8.1 Key Drivers 115
8.2 Agricultural and production issues 116 8.2.1 Agricultural Processes84 116
8.3 Manufacturing Processes 118
8.4 Example of Oil Production from canola 119
8.5 Biodiesel Production 119
8.6 Overall Cost and Energy Consumption 121
8.7 Economics for Production of Bio Diesel in Canada using Canola 122
8.8 Production of Biodiesel from Jatropha Curcas oil by using Pilot Biodiesel Plant 122
8.9 Economic Considerations for a typical USA location 123
8.10 Critical Cost Benefit Analysis of Oilseed Biodiesel in Canada 123
8.11 A Preliminary Economic Feasibility Study Commercial Biodiesel Production In South Africa 124
8.12 New and developing processes to improve economy 125 8.12.1 Waterless biodiesel promises greater efficiency 125 8.12.2 Membrane Technology in Production of Biofuels 126 8.12.3 New biodiesel process 126
8.13 Reduction in cost for biodiesel from Algae 126
8.14 Conclusion 127
Chapter 9: Recommendations for Further Research 128
9.1 Research on appropriate feed stock sources for biodiesel 128
9.2 There is need to conduct developmental research on improved technologies based on unconventional non edible feedstocks 129
9.3 Acid and Base Homogeneous Catalysts 129 9.3.1 Alkooxide Catalysts 129 9.3.2 Typical Benefits and Drawbacks of Base catalysts 130 9.3.3 Various operation parameters 130
9.3.3.1 Effect of alkaline catalyst concentration 130 9.3.3.2 Acid catalyst trans-esterification 131 9.3.3.3 Alcohol to vegetable oil molar ratio, 131 9.3.3.4 Temperature 131 9.3.3.5 Purity of the reactants (mainly water content), and free fatty acid
content effect on trans-esterification 131
9.4 Heterogeneous catalysts, continuous process 132
9.5 Development of enzymatic catalysts 132
9.6 Separation of products 133
9.7 Reactor Modification 133
9.8 Supercritical Methods 133
9.9 Adsorbents IN Biodiesel Production 134
9.10 Simulation, Modelling and Process Optimization 134
9.11 Valorization of by products 134
List of Tables
Table 2.1: Comparison of the yields in alkaline-catalyzed, acid-catalyzed and ...................... 13
Table 2.2: Compositional data of pyrolysis of oils (wt%) ........................................................... 14
Table 3.1: Annual average production of 17 oils and fats in selected five –years periods
from 1976/80 with forecasts up to 2016/20 .................................................................. 17
Table 3.2: Chemical compositions of important vegetable oils ................................................. 18
Table 3.3: Properties of Edible Vegetable Oils ............................................................................. 18
Table 3.4: Chemical composition (wt%) of soybean and its components (dry weight basis) 19
Table 3.5: Average compositions for crude and refined soybean oil ........................................ 19
Table 3.6: Melting point of fatty acids and triacyglycerols of soybean oil and its .................. 24
Table 3.7: Representative values for selected physical properties of soybean oil ................... 25
Table 3.8: Composition of Palm Oil ............................................................................................... 27
Table 3.9: Composition of major triacylglycerols of canola oils (%) ......................................... 28
Table 3.10: Some physical properties of canola and Hear oil ...................................................... 29
Table 3.11: World production and disappearance of sunflower oil (in 1000 tonnes ................ 30
Table 3.12: Specifications of Crude Sunflower Oil ........................................................................ 31
Table 3.13: Properties of bleached sunflower oil ........................................................................... 33
Table 3.14: Properties of deodorized Sunflower Oil ..................................................................... 33
Table 3.15: Summary of Statistical Analysis of Test Properties of Jatropha Samples .............. 38
Table 4.1: Reaction conditions for biodiesel synthesis using homogeneous alkali catalysis ... 42
Table 4.2: Inputs and mass requirements for the trans-esterification process .......................... 43
Table 4.3: Types of oil for biodiesel production............................................................................. 50
Table 4.4: Comparison of process intensification technologies for continuous biodiesel
production with conventional stirred tank reactors .................................................. 52
Table 4.5: Comparative analysis of different biodiesel processes ............................................... 69
Table 6.1: Simulation basis ................................................................................................................ 92
Table 6.2: MRU design specification ............................................................................................... 92
Table 7.1: Major Biodiesel Producers in India .............................................................................. 100
Table 7.2: List of the 3 demonstration projects on biodiesel in China ...................................... 102
Table 7.3: Major Biodiesel Producers in China ............................................................................ 102
Table 7.4: Biodiesel Producers in Malaysia .................................................................................. 104
Table 7.5: Biodiesel Producers in Indonesia ................................................................................. 105
Table 7.6: Major Biodiesel Producers in Australia ...................................................................... 106
Table 7.7: Biodiesel Production Growth: Brazil ........................................................................... 107
Table 7.8: Brazilian Biodiesel Exports by Country of Destination ............................................ 107
Table 7.9: Feedstock used in Brazil for biodiesel ......................................................................... 108
Table 7.10: Biodiesel Producers in Brazil ...................................................................................... 109
Table 7.11: Major Biodiesel Producers in Argentina ................................................................... 110
Table 7.12: Major Biodiesel Producers in Canada ....................................................................... 111
Table 7.13: Biodiesel Producers in USA ........................................................................................ 111
Table 7.14: EU Biodiesel Production – Main Producers (million liters) ................................... 112
Table 7.16: Feedstock used for Biodiesel Production – 1000 MT ............................................... 113
Table 7.17: Major Biodiesel Producers in Europe ........................................................................ 113
Table 8.1: Illustrative Profitability of Canola vs. Corn (At Estimated 2006 Prices ................. 118
Table 8.2: Comparison of Estimated Capital Costs ..................................................................... 123
Table 8.3: Manufacturing costs of biodiesel for various feed stocks ......................................... 124
Volume II
ANNEXURE
Annexure 1: S.P. Singh, et al., Biodiesel production through the use of different sources
and characterization of oils and their esters as the substitute of diesel: A
review, Renewable and Sustainable Energy Reviews, 2010
Annexure 2: Balat et al., Progress in biodiesel processing, Applied Energy, 2010
Annexure 3: Kraai et al., Novel highly integrated biodiesel production technology in a
centrifugal contactor separator device, 2009
Annexure 4: T. Eevera, et al., Biodiesel production process optimization and
characterization to assess the suitability of the product for varied
environmental conditions, Renewable Energy, 2009
Annexure 5: Masoud Zabeti, et al., Activity of solid catalysts for biodiesel production: A
review, Fuel Processing Technology, 2009
Annexure 6: Zheyan Qiu, et al, Process intensification technologies in continuous
biodiesel production, Chemical Engineering and Processing: Process
Intensification, 2010
Annexure 7: Dennis Y.C. Leung, et al., A review on biodiesel production using catalyzed
trans-esterification, Applied Energy, 2010
Annexure 8: Ru Yang, et al., One-pot process combining trans-esterification and selective
hydrogenation for biodiesel production from starting material of high
degree of unsaturation, Bioresource Technology, 2010
Annexure 9: J.M. Marchetti, et al., Biodiesel production from acid oils and ethanol using
a solid basic resin as catalyst, Science direct, 2010
Annexure 10: A. Deshpande, et al., Supercritical biodiesel production and power
cogeneration: Technical and economic feasibilities, Bioresource Technology,
2010
Annexure 11: Gleason, Rodney J., et al., Biodiesel Fuel and Method of Manufacture, 2009,
US Patent Application 20090277077
Annexure 12: West, J., et al., Biodiesel Production Unit, 2010, US Patent Application
20100095581
Annexure 13: Strege, Joshua R., et al., Process For The Conversion Of Renewable Oils To
Liquid Transportation Fuels, 2010, US patent application 20100113848
Annexure 14: Parnas, R., et al., Methods and systems for alkyl ester production, 2009,
Patent US7544830
Annexure 15: Lichtenberger, P.L., et al., Esterification and transesterification systems,
methods and apparatus, 2010, US Patent 7,678,340
Annexure 16: Mohammed, F., et al., Method of Biodiesel Production, 2009, US Patent
Application 20090038209
i
EExxeeccuuttiivvee SSuummmmaarryy
Diesel fuel quality is continuously undergoing improvements to meet more and more
stringent emission regulations of both automotive and other diesel engines. This in turn also
affects the demand of quality of biodiesel which is largely being looked at as a blend
component. This ever increasing demand of the quality of biodiesel has, to an extent,
necessitated innovations in its manufacturing processes. At the same time the economics of
the manufacturing process as well as considerations of minimizing the demand for process
water, time taken by the process, and, the energy economics has also brought in innovations
in the manufacturing process. Another factor that is playing a major role in process
innovation is the discovery of various new feed materials, which sometimes also affects the
process chemistry. All of the points mentioned above are catering to the fantasy of the
process developer in excelling and coming out with more novel process ideas. This has led
to some fascinating new developments in the process of manufacturing biodiesel.
In this report some of the recent developments in the area of the processes employed for
production of biodiesel have been brought out. It is understood here that the basic trans-
esterification chemistry is virtually the same as reported many years ago, but the newer
demands of catering to a wide range of Free Fatty Acids (FFAs) and other parameters as
mentioned above have made the process and its engineering more intricate.
The report has touched upon the chemistry and composition of some important feedstocks
to shed light on their significance in the process chemistry. It also includes a chapter on
current conversion technologies to make biodiesel; touches upon the trans-esterification of
triglycerides and some novel and highly integrated biodiesel production process
optimizations and their characterization to assess the suitability of the product for varied
environmental conditions; a review of activity of solid heterogeneous catalysts and non-
catalytic process for biodiesel production. The chapter also mentions process intensification
technologies in continuous biodiesel production, and, a one-pot process combining trans-
esterification and selective hydrogenation for biodiesel production from starting material of
high degree of unsaturation. Feasibility of Super-Critical biodiesel production along with
power cogeneration, biodiesel production from acid oils and ethanol using a solid basic
resin as catalyst, and the cheaper Evercat Fuels Process to manufacture biodiesel is also
mentioned. The newer reactive distillation methods and systems for allyl-ester production,
pyrolysis and cracking process for biodiesel production, and, micro-emulsification methods
also find a mention.
A chapter, to draw attention to the ever increasing importance of simulations and modelling
activities gives examples of some new researches in this area. A number of new
developments which are currently being researched are extensively mentioned with brief,
available details. The report also lists biodiesel units and production worldwide. This
information is always changing but it provides a broad picture of biodiesel production’s
global activities. A short, indicative note of production economics of biodiesel and a chapter
ii
on some areas for further research has also been included. A very large number of references
are included for the use of readers who need further detailed information.
The report thus is a brief document that brings out the state-of-the-art in this area of activity.
It may be useful to both prospective researchers as well as to the industry in considering
new directions.
.
1
IInnttrroodduuccttiioonn
Worldwide petroleum consumption has steadily increased. In 2009, the total consumption
was 4,060 million tons, with an average annual growth rate of about 1.5 % in the past 20
years. As a result, crude oil is becoming scarcer, more expensive and a highly volatile
commodity. According to BP’s annual statistical review of world energy, the proven oil
reserves were estimated at 1.7 X 105 million tons in late 2008, with a reserve to production
ratio of 42 years.
Figure 1.1: Global Oil Price and Supply trends
Source: chartingtransport.files.wordpress.com
Today, the transportation sector worldwide is almost entirely dependent on petroleum-
derived fuels. Petroleum-based products are one of the main causes of anthropogenic carbon
dioxide (CO2) emissions to the atmosphere. One-fifth of global CO2 emissions are created by
the transport sector1, which accounts for some 60% of global oil consumption2. Around the
world, there were about 806 million cars and light trucks on the road in 20073. These
numbers are projected to increase to 1.3 billion by 2030 and to over 2 billion vehicles by
1. Goldemberg J. Environmental and ecological dimensions of biofuels; Conference on the ecological dimensions of biofuels,
Washington (DC); 2008 [March 10] 2. International Energy Agency (IEA). Key world energy statistics 2008. OECD/ IEA, Paris; 2008 3. Plunkett JW. Plunkett’s automobile industry almanac 2008: automobile, truck and specialty vehicle industry market
research, statistics, trends & leading companies. Houston (Texas): Plunkett Research Ltd; 2007. 4. World Business Council for Sustainable Development (WBCSD). Mobility 2030: meeting the challenges to sustainability.
The sustainable mobility project, Geneva (Switzerland); 2004 5. Balat M, Balat M. Political, economic and environmental impacts of biomass based hydrogen. Int J Hydrogen Energy 2009;
34:3589–603.
CHAPTER 1
2
20504. This growth will affect the stability of ecosystems and global climate as well as global
oil reserves5,6.
Active research programs have been considered worldwide to reduce reliance on fossil fuels
by the use of bio-based alternative and sustainable fuel sources. One of the liquid fuels
which has attracted most attention, at present, is biodiesel. Today, apart from the
conventional seed oils and animal fats, the production of biodiesel is also being looked at
from algae and yeast derived oils, and from other biomass.
Advanced technologies are now under development to convert biomass into various forms
of secondary energy, including gaseous and liquid biofuels, electricity and even Hydrogen.
The purpose of biomass conversion is to provide fuels with clearly defined fuel
characteristics that meet given fuel quality standards. It is also necessary that these fuels can
be used in conversion devices, e.g.: IC engines, with good performance such as high
efficiency, low emissions, etc.
At the same time, their use and conversion technologies have to aim at low GHG emissions
and overall positive benefits. Depending on the conversion of biomass, in principle, three
main pathways come into consideration:
Thermo-chemical Pathway
Physical-Chemical Pathway and,
Bio-chemical Conversion Pathway
In general, after conversion, upgrading is needed for the fuels to meet required
specifications.
1.1 BIODIESEL
Biodiesel, a clean renewable fuel, has recently been considered as the best candidate
for a diesel fuel substitution because it can be used in any compression ignition
engine without the need for modification. Biodiesel is found to be environmentally
safe, non-toxic. The main advantages of using Biodiesel are its renewability, better
quality exhaust gas emission, its biodegradability and the organic carbon present in
it which is photosynthetic in origin. It does not contribute to a rise in the level of
carbon dioxide in the atmosphere and consequently to the green house effect.
Biodiesel is nonflammable and, in contrast to petrodiesel, is nonexplosive, with a
flash point of 423K for biodiesel as compared to 337K for petrodiesel. Unlike
petrodiesel, biodiesel significantly reduces toxic and other emissions when burnt as a
fuel. The advantages of biodiesel as diesel fuel are its portability, ready availability,
6. Balat M, Balat H. Recent trends in global production and utilization of bioethanol fuel. Appl Energy 2009; 86:2273–82.
3
renewability, higher combustion
efficiency, lower sulfur, lower aromatic
content, and higher cetane number.
Figure 1.2: A biodiesel outlet at a conventional
gas station
Source: static.flickr.com
Biodiesel must meet demanding product specifications. For instance, ASTM D 6751,
American Society for Testing and Materials provides, among other things, that
biodiesel have a methanol content of less than 0.2 volume percent, a water and
sediment content of no more than 0.05 volume percent, an acid number of no more
than 0.50 milligrams of potassium hydroxide per gram of biodiesel, free glycerin of
no more than 0.020 mass percent, and a phosphorus content of no more than 0.001
mass percent (calculated as elemental phosphorus). Biodiesel should also exhibit
stability in storage, particularly stability against oxidation degradation.
The main advantages of biodiesel include its domestic origin, which would help
reduce a country’s dependency on imported petroleum, its biodegradability, high
flash point, and inherent lubricity in the neat form. The major disadvantages of
biodiesel are its higher viscosity, lower energy content, higher cloud point and pour
point, higher nitrogen oxide (NOx) emissions, lower engine speed and power,
injector coking, engine compatibility, high price, and greater engine wear. The
technical disadvantages of biodiesel and fossil diesel blends include problems with
fuel freezing in cold weather, reduced energy density, and degradation of fuel under
storage for prolonged periods.
The competitiveness of biodiesel relies on the prices of biomass feedstock and costs,
which are linked to conversion technology. Depending on the feedstock used,
byproducts may have more or less relative importance. Biodiesel is not competitive
with fossil diesel under current economic conditions, where the positive externalities,
such as impacts on the environment, employment, climate changes, and trade
balance, are not reflected in the price mechanism. The economic benefits of a
biodiesel industry would include value added to the feedstock, an increased number
of rural manufacturing jobs, increased investments in plant and equipment, an
expanded manufacturing sector, an increased tax base from plant operations and
income taxes, improvement in the current account balance, and reductions in health
care costs due to improved air quality and greenhouse gas mitigation.
The production and utilization of biodiesel is facilitated firstly through the
agricultural policy of subsidizing the cultivation of nonfood crops. Secondly,
4
biodiesel is exempted from the oil tax. The European Union accounted for nearly
89% of all biodiesel production worldwide in 2005. In near future the United States
is expected to become the world’s largest single biodiesel market, accounting for
roughly 18% of world biodiesel consumption, followed by Germany. The economic
advantages of biodiesel are that it reduces greenhouse gas missions, helps to reduce
a country’s reliance on crude oil imports, and supports agriculture by providing new
labor and market opportunities for domestic crops.
The cost of biodiesel fuels varies depending on the base stock, geographic area,
variability in crop production from season to season, the price of crude petroleum,
and other factors. The high price of biodiesel is in large part due to the high price of
the feedstock. However, biodiesel can be made from other feedstock, including beef
tallow, pork lard, and yellow grease. Biodiesel is not competitive with petro diesel
under current economic conditions. The competitiveness of biodiesel relies on the
price of the biomass feedstock and costs associated with the conversion technology.
In January 2007 the European Commission published the New Energy Policy for
Europe, targeting a 10% share of biofuels in the transportation sector and raising the
share of renewable energy to a tough target of 20% by 20207. This has stimulated the
production of biofuels in Europe considerably, with biodiesel being the most
important example. The projected biodiesel consumption for 2007 was 3.8 MTOE, a
70% increase compared to 20068.
Biodiesel, also known as FAME (fatty acid methyl ester) is made from renewable
biological sources such as
vegetable oils and animal fats
Biodiesel production is a very
modern and technological area for
researchers due to the relevance
that it is winning everyday
because of the increase in the
petroleum price and the
environmental advantages9.
Biodiesel blends reduce levels of
global warming gases such as
CO2.
Figure 1.3: Rapeseed oil is a major source of biodiesel feedstock
Source: majarimagazine.com
7. International Energy Agency (IEA). Key world energy statistics 2008. OECD/ IEA, Paris; 2008 8. Plunkett JW. Plunkett’s automobile industry almanac 2008: automobile, truck and specialty vehicle industry market
research, statistics, trends & leading companies. Houston (Texas): Plunkett Research Ltd; 2007. 9. World Business Council for Sustainable Development (WBCSD). Mobility 2030: meeting the challenges to sustainability.
The sustainable mobility project, Geneva (Switzerland); 2004
5
About one hundred seventeen years ago, Rudolf Diesel tested peanut oil as fuel for
his engine for the first time on August 10, 189310. In the 1930s and 1940s vegetable
oils were used as diesel fuels from time to time, usually only in emergency due to its
properties. Vegetative oils as such cannot be used as a fuel for diesel engines, due to
their high viscosities, low volatilities and poor cold flow properties. The injection and
atomization characteristics of the vegetable oils are different than petroleum derived
diesel fuels. Modern diesel engines have fuel-injection system sensitive to viscosity
change. These problems can be avoided by reducing fuel viscosity of vegetable oil to
improve its performance.
1.2 PROJECT DELIVERABLES
This report presents information on the following key areas of the global biodiesel
sector:
Current biodiesel conversion technologies in use around the world, their
process schematics and their individual merits and shortcomings
A listing of global biodiesel production units, their production capacities and
feedstock used, and a discussion on the production trends to be expected for
the major players in the years to come
New conversion technologies currently under development
A short note on the economics of biodiesel production
Another major emerging technology to obtain a diesel substitute are Hydro-
Processed Oils, or Green Diesel. This topic has not been addressed in the report.
10. Balat M, Balat M. Political, economic and environmental impacts of biomass based hydrogen. Int J Hydrogen Energy 2009;
34:3589–603.
6
CCoonnvveerrssiioonn ttoo BBiiooddiieesseell
Biodiesel is biodegradable, nontoxic, and it significantly reduces toxic and other emissions
when burnt as a fuel.
The advantages of biodiesel as diesel fuel are its portability, ready availability, renewability,
higher combustion efficiency, non-toxicity, higher flash point, lower sulfur and aromatic
content, higher cetane number, and higher biodegradability.
Biodiesel is nonflammable and, in contrast to petrodiesel, is non-explosive, with a flash point
of 423K for biodiesel as compared to 337K for petrodiesel.
The direct use of vegetable oils and/or oil blends is generally considered to be
unsatisfactory and impractical for both direct injection and indirect type diesel engines
because of their high viscosities and low volatilities injector coking and trumpet formation
on the injectors, higher level of carbon deposits, oil ring sticking, thickening and gelling of
the engine lubricant oil, and acid composition.
The conversion of vegetable oils into biodiesel is an effective way to overcome all the
problems associated with the combustion of vegetable oils in engines.
Trans-esterification, Pyrolysis, Micro-emulsification and Dilution are the four techniques
applied to solve the problems encountered with vegetable oil utilization as a fuel.
Biodiesel is obtained by transesterifying triglycerides with methanol. Methanol is the
preferred alcohol for obtaining biodiesel because it is the cheapest alcohol.
The production processes for biodiesel are well known. There are four basic routes to
biodiesel production from oils and fats:
Base-catalyzed trans-esterification
Direct acid-catalyzed trans-esterification
Conversion of the oil into its fatty acids and then into biodiesel
Non-catalytic trans-esterification of oils and fats.
The most important aspects of biodiesel production to ensure trouble-free operation in
diesel engines are:
Complete trans-esterification reaction
Removal of glycerine
Removal of catalyst
Removal of alcohol
Removal of free fatty acids
CCHHAAPPTTEERR 22
7
These parameters are all specified through the biodiesel standard, ASTM D 6751 which are
essential for further commercial use.
2.1 TRANS-ESTERIFICATION
Trans-esterification is the reaction of a fat or oil with an alcohol to form esters and
glycerol.
A catalyst is usually used to improve the reaction rate and yield.
The general steps in biodiesel production are shown as a flow diagram in figure 2.1.
It shows the raw materials, the different steps needed to carry out processes such as
mixing of catalyst with methanol, trans-esterification reaction, purification for
biodiesel, recovery and recirculation of methanol, and recovery of byproduct
glycerine.
8
Figure 2.1: Schematic diagram of biodiesel production process
Catalyst
Methanol
Vegetable Oils, Used
Cooking Oil, Animal Fats
Neutralizing Acid
Catalyst-
Mixing
Transesterification
Neutralization
Purification
Crude Biodiesel
Phase Separation
Methanol Recovery
Recycled
Methanol
Re-neutralization Methanol-
Recovery
Quality Control
Methyl Ester
Pharmaceutical
Glycerin
Glycerin
Purification
Crude
Glycerin
If desired
9
Excess alcohol is used to shift the equilibrium towards the product because of
reversible nature of reaction.
For this purpose primary and secondary monohybrid aliphatic alcohols having 1-8
carbon atoms could be used.
2.1.1 Chemistry of trans-esterification process11
Trans-esterification consists of a number of consecutive, reversible reactions. The
triglycerides are converted step wise to triglycerides, mono-glyceride and finally
glycerol.
A mole of ester is librated at each step
Alkali catalyzed trans-esterification
In trans-esterification method, the reaction mechanism for alkali catalyzed trans-
esterification is formulated in three steps as explained in Figure 2.2.
Figure 2.2: Alkali Catalyzed Trans-esterification
11.
S.P. Singh, et al., Biodiesel production through the use of different sources and characterization of oils and their esters as the substitute of diesel: A review, Renewable and Sustainable Energy Reviews, 2010 (Annexure 1)
10
Mechanism of the alkali-catalyzed trans-esterification of vegetable oils
The first step is an attack on the carbonyl carbon atom of the triglycerides molecule
by the anion of the alcohol (Methoxide ion) to form a tetrahedral intermediate that
reacts with an alcohol (methanol) to regenerate the anion of alcohol (methoxide ion).
In the last step, rearrangement of tetrahedral intermediate results in the formation of
a fatty acid ester and a diglyceride.
When NaOH, KOH, K2CO3 or other similar catalysts were mixed with alcohol, the
actual catalysts, alkoxide group is formed.
Kim et al.12, have developed a process for the production of Biodiesel from vegetable
oils using heterogeneous catalyst Na/NaOH/Al2O3. These catalysts showed almost
the same activity under the optimized reaction conditions compared to conventional
homogeneous NaOH catalyst.
Acid catalyst trans-esterification
An alternative process is to use acid catalyst that some researchers have claimed are
more tolerant of free fatty acids. The mechanism of acid catalyzed trans-esterification
of vegetable oil (for a monoglyceride) is shown in Figure 2.3.
Figure 2.3: Mechanism of acid catalyzed trans-esterification
It can be extended to di- and triglycerides. The protonation of carbonyl group of the
ester leads to carbonation, which after a nucleophilic attack of the alcohol produces a
tetrahedral intermediate.
This intermediate eliminates glycerol to form a new ester and to regenerate the
catalyst.
12.
Kim, H.J., et al., Transesterification of vegetable oil to biodiesel using heterogeneous base catalyst. Catal Today, 93–95 (2004), pp. 315–320
11
We can use acid, alkali and biocatalyst in trans-esterification method. If more water
and free fatty acids are in triglycerides, acid catalyst can be used.
Trans-methylation occur approximately 4000 times faster in the presence of an alkali
catalyst than those catalyzed by the same amount of acidic catalyst
Lipase catalyst trans-esterification
In this trans-esterification, lipase catalyst is used.
This trans-esterification process is like alkali trans-esterification, only ratio of catalyst
and solvent and stirring time is different.
The process is explained in Figure 2.4. Lipases are known to have a propensity to act
on long-chain fatty alcohols better than on short-chain ones.
Figure 2.4: Flow diagrams comparing biodiesel production using lipase-catalysis
Non-catalytic trans-esterification methods13
There are two routes to produce biodiesel by non-catalyzed trans-esterification:
BIOX co-solvent process and
Supercritical alcohol process
BIOX co-solvent process
Co-solvent options are designed to overcome slow reaction time caused by the
extremely low solubility of the alcohol in the triglyceride phase. One approach that
uses either tetrahydrofuran (THF) or methyl tetra-butyl ether (MTBE) as a co-solvent
to generate a one-phase system.
The result is a fast reaction, on the order of 5–0 min, and no catalyst residues in either
the ester or the glycerol phase.
The THF co-solvent is chosen, in part, because it has a boiling point very close to that
of methanol. This system requires a rather low operating temperature, 303 K.
13.
Mustafa Balat, et al, Progress in biodiesel processing, Applied Energy, 2010 (Annexure 2)
12
Supercritical alcohol trans-esterification
The trans-esterification of triglycerides by supercritical methanol, ethanol, propanol
and butanol has proved to be the most promising process. Saka and Kusdiana14, and
Demirbas15 first proposed that biodiesel fuels may be prepared from vegetable oil via
non-catalytic trans-esterification with supercritical methanol.
Saka and Kusdiana14 have proposed that the reactions of rapeseed oil were complete
within 240 s at 623 K, 19 MPa, and molar ratio of methanol to oil at 42.
To achieve more moderate reaction conditions, further effort through the two-step
preparation was made by Kusdiana and Saka16.
In this method, oils/fats are, first, treated in subcritical water for hydrolysis reaction
to produce fatty acids. After hydrolysis, the reaction mixture is separated into oil
phase and water phase by decantation.
The oil phase (upper portion) is mainly fatty acids, while the water phase (lower
portion) contains glycerol in water. The separated oil phase is then mixed with
methanol and treated at supercritical condition to produce methyl esters thorough
esterification.
After removing unreacted methanol and water produced in reaction, FAME can be
obtained as biodiesel.
Methyl esterification of fatty acids is a major reaction to produce FAME in the two-
step supercritical methanol method, whereas trans-esterification of triglycerides is a
major one in the conventional alkali- and acid-catalyzed methods. This esterification
reaction is, therefore, an important step for high quality biodiesel fuel production.
Non-catalytic trans-esterification reactions at high temperature and pressure
conditions provide improved phase solubility, decrease mass-transfer limitations,
provide higher reaction rates and make easier separation and purification steps.
Besides, the supercritical trans-esterification method is more tolerant to the presence
of water and FFAs than the conventional alkali-catalyzed technique, and hence more
tolerant to various types of vegetable oils, even for fried and waste oils. Comparison
of the yields in alkaline-catalyzed, acid-catalyzed and supercritical methanol is given
in the Table 2.1.
14. S. Saka, D. Kusdiana. Biodiesel fuel from rapeseed oil as prepared in supercritical methanol. Fuel, 80 (2001) 15. A. Demirbas. Biodiesel from vegetable oils via transesterification in supercritical methanol. Energy Convers Manage, 43
(2002) 16. D. Kusdiana, S. Saka. Two-step preparation for catalyst-free biodiesel fuel production: hydrolysis and methyl
esterification. Appl Biochem Biotechnol, 115 (2004)
13
Table 2.1: Comparison of the yields in alkaline-catalyzed, acid-catalyzed and
supercritical methanol13
Raw material FFA* content
(wt%)
Water content
(wt%)
Yields of methyl esters (wt%)
Alkaline-
catalysed
Acid-
catalyzed SCMb
Rapessed oil 2.0 0.02 97.0 98.4 98.5
Palm oil 5.3 2.1 94.4 97.8 98.9
Frying oil 5.6 0.2 94.1 97.8 96.9
Waste palm oil >20.0 >61.0 - - 95.8
* FFA – free faty acid
bSCM – supercritical methanol
2.2 PYROLYSIS11
Pyrolysis is a method of conversion of one substance into another by means of heat
or by heat with the aid of the catalyst in the absence of air or oxygen. The process is
simple, wasteless, pollution free and effective compared with other cracking
processes. The reaction of thermal decomposition is shown in Figure. 2.5.
The goal of pyrolysis is the optimization of high-value fuel products from biomass
by thermal and catalytic means. The pyrolyzed material can be any type of biomass,
such as vegetable oils, animal fats, wood, bio-waste, etc.
Conversion of vegetable oils and animal fats composed predominantly of
triglycerides using pyrolysis type reactions represents a promising option for the
production of biodiesel. Many investigators have reported the pyrolysis of
triglycerides to obtain products suitable for diesel engines.
Thermal decomposition of triglycerides produces the compounds of classes
including alkanes, alkenes, alkadienes, aromatics and carboxylic acids.
Different types of vegetable oils produce large differences in the composition of the
thermally decomposed oil13.
The mechanism of thermal decomposition of triglycerides as shown in Figure. 2.5
below was proposed by Schwab et al17. Mechanisms for the thermal decomposition
of triglycerides are likely to be complex because of the many structures and
multiplicity of possible reactions of mixed triglycerides.
17.
Schwab, A.W. et al., Diesel fuel from thermal decomposition of soybean oil. J Am Oil Chem Soc, 65 (1988)
14
Figure 2.5: The mechanism of thermal decomposition of triglycerides
Generally, thermal decomposition of these structures proceeds through either a free-
radical or carbonium ion mechanism.
The formation of aromatics is supported by a Diels–Alder addition of ethylene to a
conjugated diene formed in the pyrolysis reaction.
Carboxylic acids formed during the pyrolysis of vegetable oils probably result from
cleavage of the glyceride moiety.
The compositions of pyrolyzed oils are listed in Table 2.2. The main components
were alkanes and alkenes, which accounted for approximately 60% of the total
weight. Carboxylic acids accounted for another 9.6–16.1%.
Table 2.2: Compositional data of pyrolysis of oils (wt%)
High oleic safflower Soybean oil
N2 sparge Air N2 sparge Air
Alkanes 37.5 40.9 31.1 29.9
Alkanes 22.2 22.0 28.3 24.9
Alkadienes 8.1 13.0 9.4 10.9
Carboxylic acids 11.5 16.1 12.2 9.6
Unresolved unsaturates 9.7 10.1 5.5 5.1
Aromatics 2.3 2.2 2.3 1.9
Unidentified 8.7 12.7 10.9 12.6
The soaps obtained from the vegetable oils can be pyrolyzed into hydrocarbon-rich
products.
The saponification and pyrolysis of sodium soap of vegetable oil proceed as follows:
15
Saponification:
Pyrolysis of sodium soaps:
The soaps obtained from the vegetable oils can be pyrolyzed into hydrocarbon-rich
products with higher yields at lower temperatures.
Demirbas15 investigated the yields of decarboxylation products by pyrolysis from
sodium soaps of four vegetable oils. The maximum decarboxylation products were
obtained from pyrolysis of sunflower oil (97.5%), corn oil (97.1%), cottonseed oil
(97.5%), and soybean oil (97.8%) at 610 K.
The production of bio-fuels (especially bio-gasoline) from vegetable oils by catalytic
cracking is a promising alternative. Several vegetable oils (e.g. palm, canola,
soybean) have been employed in the process that involves conversion of the oils into
biofuels. Non catalytic supercritical process of trans-esterification, addition of
solvents to make homogeneous phases, catalytic distillation are other processes to
produce biodiesel and have been discussed in detail in chapters four and five.
16
FFeeeeddssttoocckk ffoorr PPrroodduuccttiioonn ooff BBiiooddiieesseell
Chemically, biodiesel is a mixture of methyl esters with long-chain fatty acids and is
typically made from nontoxic, biological resources such as vegetable oils18, animal fats19, or
even used cooking oils (UCO)20.
The raw material for the manufacture of biodiesel
being exploited commercially by the developed
countries constitutes the edible fatty oils derived
from rapeseed, soybean, palm, sunflower, coconut,
linseed, etc.21. Use of such edible oils to produce
biodiesel in India is not feasible in view of a big
gap in demand and supply of such oils in the
country.
18. Abreu FR, Lima DG, Hamú EH, Wolf C, Suarez PAZ. Utilization of metal complexes as catalysts in the transesterification
of Brazilian vegetable oils with different alcohols. J Mol Catal A Chem 2004;209:29–33.
Azcan N, Danisman A. Microwave assisted transesterification of rapeseed oil. Fuel 2008;87:1781–8.
Berchmans HJ, Hirata S. Biodiesel production from crude Jatropha curcas L. seed oil with a high content of free fatty acids.
Bioresour Technol 2008;99:1716–21.
Bernardo A, Howard-Hildige R, O’Connell A, Nichol R, Ryan J, Rice B, et al. Camelina oil as a fuel for diesel transport
engines. Ind Crops Prod 2003;17:191–7.
Byun MW, Kang IJ, Kwon JH, Hayashi Y, Mori T. Physicochemical properties of soybean oil extracted from [gamma]-
irradiated soybeans. Radiat Phys Chem 1995;46:659–62.
Chitra P, Venkatachalam P, Sampathrajan A. Optimisation of experimental conditions for biodiesel production from
alkali-catalysed transesterification of Jatropha curcus oil. Energy Sustain Dev 2005;9:13–8.
Demirbas A. Biodiesel fuels from vegetable oils via catalytic and non-catalytic supercritical alcohol transesterifications and
other methods: a survey. Energy Convers Manage 2003;44:2093–109.
Kaya C, Hamamci C, Baysal A, Akba O, Erdogan S, Saydut A. Methyl ester of peanut (Arachis hypogea L.) seed oil as a
potential feedstock for biodiesel production. Renew Energy 2009;34:1257–60.
Issariyakul T, Kulkarni MG, Meher LC, Dalai AK, Bakhshi NN. Biodiesel production from mixtures of canola oil and used
cooking oil. Chem Eng J 2008;140:77–85.
Kansedo J, Lee KT, Bhatia S. Cerbera odollam (sea mango) oil as a promising non-edible feedstock for biodiesel
production. Fuel 2009;88:1148–50.
Kumar Tiwari A, Kumar A, Raheman H. Biodiesel production from Jatropha oil (Jatropha curcas) with high free fatty
acids: an optimized process. Biomass Bioenergy 2007;31:569–75.
Rao Y, Xiang B, Zhou X, Wang Z, Xie S, Xu J. Quantitative and qualitative determination of acid value of peanut oil using
near-infrared spectrometry. J Food Eng 2009;93:249–52.
Sahoo PK, Das LM. Process optimization for biodiesel production from Jatropha, Karanja and Polanga oils. Fuel
2009;88:1588–94. 19. Chisti Y. Biodiesel from microalgae. Biotechnol Adv 2007;25:294–306.
Ozaktas T. Compression ignition engine fuel properties of a used sunflower oil–diesel fuel blend. Energy Source
2000;22:377–82.
Hariharan VS, Reddy KV, Rajagopal K. Study of the performance, emission and combustion characteristics of a diesel
engine using sea lemon oil based fuels. Indian J Sci Technol 2009;2:43–7.
Hameed BH, Goh CS, Chin LH. Process optimization for methyl ester production from waste cooking oil using activated
carbon supported potassium fluoride. Fuel Process Technol 2009;90:1532–7. 20. Goodrum JW, Geller DP, Adams TT. Rheological characterization of animal fats and their mixtures with #2 fuel oil.
Biomass Bioenergy 2003;24: 249–56. 21. Wibulswas P, Chirachakhrit S, Keochung U, Tiansuwan J. Combustion of blends between plant oils and diesel oil. Renew
Energy 1999;16: 1098–101.
CCHHAAPPTTEERR 33
Figure 3.1: Waste Cooking Oil
Source: www.heatingoil.com/
17
Increased pressure to augment production of edible oil has also put limitation on the use of
these oils for production of biodiesel. Under such conditions, crops that produce non-edible
oils in appreciable quantities can be grown in large scale on marginal and wastelands22. A
long list of trees and shrubs is available in plenty in India, which can be exploited for fuel
production.
3.1 EDIBLE VEGETABLE OILS
Biodiesel has been mainly produced from edible vegetable oils all over the world.
More than 95% of global biodiesel production so far is from edible vegetable oils23.
Table 3.1: Annual average production of 17 oils and fats in selected five –year periods from
1976/80 with forecasts up to 2016/20
Annual Production 1976/80 1986/90 1996/00 2006/10 2016/20
World total 52.65 75.66 105.06 165.65 184.77
Soyabean oil 11.23 15.28 23.14 33.60 41.12
Cottonseed oil 2.83 3.64 4.00 5.35 6.51
Groundnut oil 3.01 3.70 4.55 5.72 6.38
Sunflower seed oil 4.21 7.25 9.11 12.43 16.97
Rapeseed oil 3.01 7.51 12.64 17.72 22.69
Sesameseed oil 0.51 0.64 0.70 0.86 0.96
Corn oil 0.83 1.35 1.91 2.49 3.16
Olive oil 1.68 1.80 2.47 2.75 2.98
Palm oil 3.69 9.22 18.72 31.43 43.36
Palmkernel oil 0.46 1.21 2.34 3.84 5.28
Coconut oil 2.85 3.07 3.01 3.70 4.55
Butter 5.60 6.35 5.81 6.93 7.99
Lard 4.25 5.17 6.38 7.93 9.14
Fish oil 1.13 1.53 1.25 1.18 11.59
Linseed oil 0.79 0.73 0.70 0.81 0.97
Castorseed oil 0.32 0.40 0.46 0.71 0.78
Tallow 6.24 6.79 7.85 10.06 10.76
Source: Mielke 2002
22. Krishna BM, Mallikarjuna JM. Properties and performance of cotton seed oil– diesel blends as a fuel for compression
ignition engines. J Renew Sustain Energy 2009;1:1–10. 23. Knothe G, Dunn RO, Bagby MO. Biodiesel: the use of vegetable oils and their derivatives as alternative diesel fuels. In:
ACS symposium series no. 666: fuels and chemicals from biomass, Washington (DC); 1997. p. 172–208.
18
3.2 COMPOSITION OF EDIBLE VEGETABLE OILS
All vegetable oils are a mixture of several fatty acids in varying percentages.
Presence of these gives each its individual characteristics. Table 3.2 below highlights
the compositions of the major edible vegetable oils in production.
Table 3.2: Chemical compositions of important vegetable oils
Type of Fatty Acid
Co
con
ut
Co
rn
Co
tto
nse
ed
Sa
fflo
we
r
Se
sam
e
So
yb
ea
n
Su
nfl
ow
er
Re
fin
ed
pa
lm
Ca
no
la
C8:00 Caprylic 5-9
C10:00 Caprylic 4-10
C12:00 Lauric 44-52
C14:00 Myristic 13-21 1 max 0.5-2.0 <1 <0.5 <0.5 <1.0 0.5-5.9
C16:00 Palmitic 8-11 8-19 17-29 2-10 7-12 7-12 2-10 32-47 3-6
C16:1 Palmitoleic <0.5 <1.5 <0.5 <0.5 <1.0
C18:0 Stearic 1-4 0.54 1-4 1-10 3.5-6 2.0-5.5 1-10 2-8 1-4
C18:1 Oleic 5-8 19-50 13-44 7-42 35-50 19-30 14-65 34-44 55-75
C18:2 Linoleic 2.5 max 34-65 40-63 72-81 35-50 48-58 20-75 7-12 15-25
C18:3 Linolenic <2.0 0.1-2.1 <1.5 <1.0 5-9 <1.5 8-22
C18:1 Ricinoleic
C20:0 Arachidic 0.4 max <1.0 0.5 max <0.5 <1.0 <1.0 <1.0
C20:1 Gradoleic <0.5 0.5 max <0.5 <0.5 <1.0 <0.5
C20:4 Arachidonic
C22:0 Behenic 0.5 max <0.5 <1.0
C22:1 Erucic (max) 2 MAX
C24:0 Lignoceric <0.5 <0.5
Given their compositions, each vegetable oil has some unique properties. For
scientific and industrial use, the following properties and values (Table 3.3) are
deemed important.
Table 3.3: Properties of Edible Vegetable Oils
Characteristic
Co
con
ut
Co
rn
Co
tto
nse
ed
Sa
fflo
we
r
Se
asa
me
So
ya
-be
an
Su
nfl
ow
er
Re
fin
d p
alm
Ca
no
la
Colour Gardner (max) 3 5 5 3 4 4 3 4 4
Acid Value (max) 0.25 0.25 0.25 0.25 0.25 0.2 0.25 .02 .02
Lodine value (Hanus) 5-11 102-130 109-120 135-150 103-116 120-143 110-143 50-55 110-120
Saponification value 250-264
187-193 190-198 186-194 188-195 180-200 188-194 192-209
186-198
Specific Gravity@250C 0.917-0.922
0.914-0.921
0.915-0.921
0.919-0.924
0.916-0.921
0.917-0.921
0.915-0.920
0.910-0.919
0.910-0.918
19
The next section takes a closer look at some of these edible oils.
3.3 SOYBEAN OIL24
Soybean is the dominant oilseed produced in the world, due to its favorable
agronomic characteristics, its high-quality protein, and its valuable edible oil. It
contributes over a half of all oilseeds produced worldwide. The US ranks first in
soybean production (8.24 million tonnes), followed by Brazil, Argentina, China and
EU-15 (4.28, 3.28, 3.26 and 2.87 million tonnes).
3.3.1 Composition of Soybean Oil
Oil recovered by solvent extraction or mechanical pressing is termed crude soybean
oil and contains various classes of lipids. It consists primarily of neutral lipids,
which include tri-, di- and monoacylglycerols, free fatty acids, and polar lipids such
as phospholipids. It also contains a minor amount of unsaponifiable matter that
includes phytosterols, tocopherols, and hydrocarbons such as phospholipids. It also
contains a minor amount of unsaponifiable mater that includes phytosterols,
tocopherols, and hydrocarbons such as Squalene. Trace metals are found in soybean
oil in ppm concentration. When the oil is refined, concentrations of all minor
constituents are reduced.
Table 3.4: Chemical composition (wt%) of soybean and its components (dry weight basis)
Components Yield Protein Oil Ash Carbohydrate
Whole seed 100.0 40.3 21.0 4.9 33.9
Cotyledon 90.3 42.8 22.8 5.0 29.4
Hull 7.3 8.8 1.0 4.3 85.9
Hypocotyls 2.4 40.8 11.4 4.4 43.4
Source: Perkins EG (1995). Composition of soybean and soybean products. In:
Practical Handbook of Soybean Processing and Utilization, Erickson DR (ed). AOCS
Press, Champaign
Table 3.5: Average compositions for crude and refined soybean oil
Components Crude oil Refined oil
Triacylglycerols (%) 95-97 >99
Phospholipids (%) 1.5-2.5 0.003-0.045
Unsaponifiable matter (%) 1.6 0.3
Phystosterols 0.33 0.13
24. Gunstone, F.D., Vegetable Oils in Food Technology : Composition, Properties and Uses, Blackwell Publishing Ltd.
20
Components Crude oil Refined oil
Tocopherols 0.15-0.21 0.11-0.18
Hydrocarbons 0.014 0.01
Free fatty acids (%) 0.3-0.7 <0.05
Trace metals
Iron (ppm) 1.3 0.1-0.3
Copper (ppm) 0.03-0.05 0.02-0.06
Source: Pryde, E.H., 1980. Composition of soybean oil. In Handbook of Soy Oil
Processing and Utilization, AOCS Press, Champaign
3.3.2 Oil extraction from Soybean
The two common processes for soybean oil extraction are solvent extraction and
mechanical pressing but in the US less than 1% of the soybeans is processed by
mechanical means. Solvent extraction with hexane is the standard practice.
Solvent (hexane) extraction of soybeans is a diffusion process achieved by immersing
solid in solvent or by percolating solvent through a bed of solids. Rotary (deep-bed),
horizontal belt, and continuous loop extractors are used for soybeans Solvent is
recovered from the mixture of solvent and extracted oil (miscella) by double-effect
evaporator and steam stripping and from flake by a desolventizer-toaster, and is
recycled.
Figure 3.2: Soybean produce and kernels
3.4 PHYSICAL PROPERTIES OF SOYBEAN OIL
3.4.1 Polymorphism
Oils and fats go through a series of increasingly organized crystal phases upon
cooling. This multiple form of crystallization (polymorphism) is an important
characteristic of fats and oils because it greatly influences the textural and functional
properties of fats and fat-based products.
The three commonly observed fat crystal forms are α, β’, and β forms. The β’ form,
with small and needle-like crystals which form smooth and fine-grained structures,
21
is the most desired form in shortening and margarine applications. Oil composition
plays an important role in crystal formation. Unmodified soybean oil has a tendency
to form β-crystals but the hydrogenated soybean oil can be crystallized in the β’
form. Controlled crystallization (under defined conditions of temperature, time and
mixing) and tempering is used to manipulate or stabilize the crystal forms to achieve
products with the desired functional properties.
3.4.2 Density
Most information concerning the physical properties of soybean and other vegetable
oils comes from early work, but there have been recent developments in establishing
mathematical models to predict changes in physical properties with fatty acid
composition and temperature.
For vegetable oils, it has been shown that density decreases linearly with increase in
temperature
ρ =b + mT
where ρ is the density, T is the temperature, and b and m are constants. These
constants are different for different oils. A widely used method for density prediction
of vegetable oils was developed by Lund and discussed by Halvorsen and co-
workers (1993). The Lund relationship is:
sg (15◦C)=0.8475 + 0.00030 SV + 0.00014 IV
where sg is the specific gravity of vegetable oil at 15◦C, SV is the saponification value,
and IV is the iodine value of the oil.
This equation can be used for a wide variety of oils. A generalized method of density
estimation, which was developed by Rodenbush and co-workers (1999)25, was also
extended to predict oil viscosity, thereby relating these two key physical properties.
3.4.3 Viscosity
The effect of temperature on viscosity of various vegetable oils and fatty acids was
investigated by Noureddini and co-workers (1992)26. The relationship was expressed
as:
ln µ=A + B/(T + C)
In which µ is viscosity in centipoises, A, B and C are constants and T is temperature
in Kelvin. For each oil and fatty acid, there is a set of constants that can be used to
predict how temperature affects viscosity of individual oils. Viscosity of fatty
25. Rodenbush, C.M., et al., 1999. Density and viscosity of vegetable oils. Journal of American Oil Chemists’ Society 76 26. Noureddini, H., et al., 1992. Viscosities of vegetable oils and fatty acids. Journal of American Oil Chemists’ Society 69
22
systems was also predicted by Rabelo and co-workers (2000)27, using the same
temperature–viscosity relationship. The set of A, B and C values for each fatty
compound class was then correlated with the number of carbon atoms and double
bonds, and rather complicated relationships were established.
Wang and Briggs28 studied viscosity of soybean oils with modified fatty acid
composition. The viscosity was expressed as:
in which R is the universal gas constant, T is temperature in Kelvin, and Ea is energy
of activation.
The concept of effective carbon number was used to describe acyl chain length and
degree of unsaturation, and was correlated with viscosity and Ea. Linear
relationships were established indicating that the more the saturation or the longer
the fatty acyl chains, the more viscous the oil and the faster the viscosity changes
with temperature.
3.4.4 Refractive index
The refractive index (RI) is a parameter that relates to molecular weight, fatty acid
chain length, degree of unsaturation, and degree of conjugation. A mathematical
relationship between refractive index and iodine value (IV) has been described by
Perkins (1995)29 as:
The reverse relationship can be used to calculate the iodine value of crude soybean
oil when the RI is known. RI was shown to increase by 0.000385 for each degree rise
of temperature.
3.4.5 Specific heat
Specific heat (Cp, in J/g K) of vegetable oil is influenced by temperature as described
in the following equation:
Cp =1.9330 + 0.0026 T
Liquid specific heat capacity for fatty acids, triacylglycerols, and vegetable oils was
estimated based on their fatty acid composition. A Rowlinson–Bondi equation was
used to estimate specific heat (Cp) for pure fatty acid. The liquid specific heat
capacities of oils were estimated by using mixture properties corresponding to the
27. Rabelo, J., et al., 2000. Viscosity prediction for fatty systems, Journal of American Oil Chemists’ Society 77 28. Wang, T. and Briggs, J.L., 2002. Rheological and Thermal properties of soybean oil with modified FA composition. Journal
of American Oil Chemists’ Society 79 29. Perkins, E.G., Physical properties of Soybean. In: Practical Handbook of Soybean Processing and Utilization, Erickson DR
(ed). AOCS Press, Champaign
23
fatty acid composition and a correction factor, which accounts for the TAG form. The
Rowlinson–Bondi equation used is as follows:
where Cp is the liquid specific heat capacity, C0p is the ideal gas specific heat
capacity, R is the universal gas constant, Tr is the reduced temperature, and ω is the
acentric factor. C0p is calculated using
The constants a, b, c and d for various chemical groups were used to calculate the
ideal gas capacity for pure fatty acids. The reduced temperature is calculated as Tr
=T/Tc (critical temperature). For a vegetable oil with xi being the molar fraction of a
fatty acid that has Cp0i,
A factor was used to correct the difference between calculated and experimental
values as derived from Morad’s study. For MW>850, as in our sample, Correction
factor (F) =−0.2836 − 0.0005(MW − 850) Cp (estimated for oil) =Cp (calculated for
mixed fatty acid) + F
The accuracy of Morad’s estimation method was determined to be ±5%. This model
was used by Wang and Briggs28 to estimate Cp of soybean oils with modified fatty
acid composition at various temperatures. All oils had the same slope of 0.0024, but
the constant ranged from 1.7992 to 1.8583, compared with a slope of 0.0026 and a
constant of 1.9330 from Formo’s equation.
3.4.6 Melting point
The melting points (m.p.) of TAGs are related to the fatty acids present. For fatty
acids, melting point depends on chain length and the number and position of double
bonds. It increases with increasing chain length and decreases with increasing cis
unsaturation. The trans form has a significantly higher melting point than its cis
isomer. Polymorphism is an important factor affecting melting point. The melting
points of fatty acids and their triacylglycerols of soybean oil and partially
hydrogenated soybean oil are presented in Table 3.6.
24
Table 3.6: Melting point of fatty acids and triacyglycerols of soybean oil and its
partially hydrogenated product
Triacylglycerol
Fatty acid Melting point (oC)
Name Melting point (oC) Composition* Form ’ Form
Palmitic 62.9 PPP 65.5 56.0
Stearic
69.6 SSS 73.0 65.0
SPP 62.5 59.5
PSP 68.0 65.0
SPS 68.0 64.0
Oleic
16.3 OOO 5.5 - 12.0
POP 35.2 30.4
SOS 41.6 37.6
POO 19.0 -
SOO 23.5 -
Elaidic 43.7 EEE 42.0 37.0
Linoleic -6.5 LLL -13.1 -
Linolenic -12.8 LnLnLn -24.2 -
Source: Sipos and Szujaj 1996. Soybean Oil. In: Bailey’s Industrial Oil and Fat Products:
general Applications. John Wiley and Sons Inc.
P=Palmitic, S=Stearic, O=Oleic, L=Linolenic, E=Elaidic acid
3.4.7 Heat of combustion
A general equation linking the heat of combustion of vegetable oils to IV and SV (i.e.
average fatty acid composition) has been developed by Bertram (Perkins 1995)29:
Therefore, the higher the degree of saturation and the longer the fatty acylgroups, the
higher the energy content of the oil.
3.4.8 Smoke, flash and fire points
These parameters are related to the free fatty acid content of oils because fatty acids
have higher vapor pressure than the triacylglycerols. Smoke point is the temperature
at which smoke is first seen. Flash point is the temperature at which the volatiles are
produced in amounts that ignite but do not support a flame. Fire point is the
temperature at which the volatiles are produced in a quantity that will support a
flame. These temperatures are lower for oils with a higher free fatty acid content or
with short chain free fatty acids.
25
3.4.9 Solubility
Soybean oil is miscible with many non-polar organic solvents. The solubility
characteristics of vegetable oils in various solvents can be estimated from their
dielectric constants or solubility parameters.
Anhydrous or aqueous ethanol is not a good solvent for soybean oil at ambient
temperature. Solubility increases with temperature until the critical solution
temperature is reached, at which point the oil and ethanol become miscible. The
solubility of oxygen in soybean oil contributes to the oxidative stability of the oil. It
varies from 1.3 to 3.2 ml/100 ml in refined and crude oils. The solubility of water in
soybean oil is about 0.071% at −10C and 0.141% at 320C.
3.4.10 Plasticity and ‘spreadability’
The most important functionality of a solidified oil and fat is its plasticity,
consistency or ‘spreadability’. A shortening or margarine product may appear to be
in a homogeneous solid state, but it consists of discrete solid (crystal particles)
dispersed in a liquid (oil) phase. The essential conditions for plasticity are proper
proportions of solid and liquid phase, and the solid particles have to be very fine so
the mass is held together by internal cohesive forces. SFI and SFC measurements may
be used to describe plasticity and ‘spreadability’.
3.4.11 Electrical resistivity
Certain industrial applications of soybean oil, such as printing ink, require high
electrical resistivity to maintain the sharpness of the image. There is limited
information on electrical properties of oil, and most deal with its dielectric
properties. Resistivity is the resistance to current passing through the material and
factors such as temperature, applied voltage and charging time will affect the value.
Polar minor components including FFA, PLs, monoacylglycerol, tocopherols,
phytosterols, β-carotene, peroxides and water all decrease the resistivity of purified
soybean oils and of soybean oil methyl esters. Selected physical properties of
soybean oil are summarized in Table 3.7.
Table 3.7: Representative values for selected physical properties of soybean oil
Property Value
Specific gravity (25oC) 0.9175a
Refractive index, nD25 1.4728b
Specific refraction, rD25 0.3054
Viscosity (centipoises at 25 oC) 50.09a
Solidification point (oC) -10 to -16
26
Property Value
Specific heat (cal/g at 19.7oC) 0.458
Heat of combustion (cal/g) 9478c
Smoke point (oC) 234
Flash point (oC) 328
Fire point 363
aIV=132.6, bIV=130.2, cIV=131.6.
Source: Pryde, E.H., 1980. Composition of soybean oil. In Handbook of Soy Oil
Processing and Utilization, AOCS Press, Champaign
3.5 OXIDATIVE QUALITIES OF SOYBEAN OIL
Soybean oil is a polyunsaturated or linoleic type of oil that is highly susceptible to
lipid oxidation. The rate of lipid oxidation depends primarily on the fatty acid
composition and only secondarily on the stereospecific distribution of the fatty acyl
groups, as described earlier.
3.6 PALM OIL24
Oil Palm originated in South
Africa but was introduced to
East Asia in 1884. Now it is
extensively cultivated for
commercial purposes in
Indonesia and Malaysia.
Figure 3.3: Oil Palm fruit
Source: www.seedol.com
The Malaysian Palm Oil Board (MPOB), formerly known as PORIM, has the largest
collection of oil palm germplasms in the world. The present planting material is
mainly dura x pisera (D x P) (tenera). Commercial planting in Malaysia have been
based on this D x P material as it gives the highest oil yield per bunch (22.5 – 22.5%).
The oil palm is the most efficient oil-production plant, with about 4.5 tonnes of oil
per hectare per year. The palm bears fruit in the third year of planting in the field,
and continues for about 25 years. Two types of oil are obtained from the oil palm
fruit: palm oil from the mesocarp and kernel oil from the kernel inside the nut.
27
3.6.1 Composition and properties of Palm Oil
Palm oil has a balanced fatty acid composition in which the level of saturated fatty
acids is almost equal to that of the unsaturated fatty acids (Table 3.8). Palmitic acid
(44-45%) and oleic acid (39-40%) are the major component acids along with linoleic
acid (10-11%) and only a trace amount of linolenic acid.
Table 3.8: Composition of Palm Oil
Malaysian (1981)a Malaysian (10990)b Brazilian (1993)c
Mean Range (215
samples) Mean
Range (244
samples) Mean
Range (73
sampels)
Fatty acids % by wt
12:0 0.2 0.1-1.0 0.2 01-0.4 0.2 Tr-2.6
14:0 1.1 0.9-1.5 1.1 1.0-1.4 0.8 Tr-1.3
16:0 44.0 41.8-46.8 44.1 40.9-47.5 39.0 31.9-57.3
16:1 0.1 0.1-0.3 0.2 0-0.4 0.03 Tr-0.4
18:0 4.5 4.2-5.1 4.4 3.8-4.8 5.0 2.1-6.4
18:1 39.2 37.3-40.8 39.0 36.4-41.2 43.2 33.8-47.5
18:2 10.1 9.1-11.0 10.6 9.2-11.6 11.5 6.4-14.8
18:3 0.4 0-0.6 0.3 0-0.6 0.4 Tr-0.7
20:0 0.4 0-0.7 0.2 0-0.4 0.01 Tr-0.3
Triacylglycerols by carbon number
C46 0.8 0.4-1.2 1.2 0.7-2.0 NA
C48 7.4 4.7-10.8 8.1 4.7-9.7 NA
C50 42.6 40.0-45.2 39.9 38.9-41.6 NA
C52 40.5 38.2-43.8 38.8 37.1-41.1 NA
C54 8.8 6.4-11.4 11.4 10.3-12.1 NA
C56 ND ND 0.6 0.5-0.8 NA
Iodine value 53.3 51.0-55.3 52.1 50.1-54.9 58.0 50.3-62.9
SMP (0C) 36.0 32.3-39.0 36.7 33.0-39.0 NA NA
ND = not detectable.
NA = not available.
Palm oil’s low levels of linoleic acid and virtual absence of linolenic acid make it relatively
stable to oxide deterioration.
3.7 CANOLA/RAPESEED OIL24
Canola oil (low-erucic acids and low-glucosinolate rapeseed oil) is now held by some
to be the best nutritional edible oil available. This oil was developed after significant
improvement and modification of the original High-Erucic Acid Rapeseed Oil
(HEAR). The level of erucic acid has been reduced to below 2% (and usually below
1%) of the total fatty acids.
28
Rapeseed species used to produce canola oil and meal are from the Brassica genus in
the Cruciferae family. They were first cultivated in the India almost 4000 years ago.
Large-scale planting of rape oilseed was first reported in Europe in the thirteenth
century. The Brassica species probably evolved from the same common ancestor as
wild mustard (Sinapis), radish (Raphanus) and arrugala (Eruca).
3.7.1 Composition
Table 3.9: Composition of major triacylglycerols of canola oils (%)
Triacylglycerols Canola (CO) LLCO HOCO
LnLO 7.6 1.7 1.5
LLO 8.6 11.0 1.1
LnOO 10.4 2.6 8.6
LnOP 2.1 0.5 1.1
LOO 22.5 28.4 12.7
LOP 5.7 4.2 2.2
OOO 22.4 32.8 49.8
POO 4.6 32.8 49.5
SOO 2.6 2.4 5.0
PPP 0.1 1.4 2.8
LLP 1.4 1.1 0.8
LOS 1.6 1.9 1.0
LLL 1.3 1.6 0.2
LnLL 1.4 0.0 0.3
LnLnO 1.7 0.4 0.1
Others 6.0 5.2 5.4
Abbreviations: LLCO – low – linolenic canola oil, HOCO – high –oleic canola oil,
linolenic, L-linoleic, O-oleic, S-stearic, P-palmitic, Others- group of 15 triacylglycerols
with contribution below 1% each. Symbols such as POS (etc) represent all glycerol
ester containing these three acyl chains.
The stability of canola oil is limited mostly by the presence of linolenic acid,
chlorophyll and its decomposition products and other minor components with high
chemical reactivity, such as trace amounts of fatty acids with more than three double
bonds. These highly unsaturated fatty acids can be formed during refining and
bleaching.
The presence of 7-11% of linolenic acid in the triacylglycerols of canola oil places it in
a similar category to soybean oil with respect to flavor and oxidative stability. The
deterioration of flavor as the result of auto – and photo – oxidation of unsaturated
fatty acids in oils and fats is referred to as oxidative rancidity.
29
3.7.2 Physical and Chemical properties of Canola Oil
Table 3.10: Some physical properties of canola and Hear oil
Parameter Canola Hear
Relative density (g/cm3; 20oC/water at 20oC) 0.914-0.917 0.907-0.911
Refractive index (nD 40 oC) 1.465-1.467 1.465-1.469
Crismer value 67-70 80-82
Viscosity (kinematic at 20 oC, mm2/sec 78.2 84.6
Cold test (15h at 4 oC) Passed Passed
Smoke point (oC) 220-230 226-234
Flash point, open cup (oC) 275-290 278-282
Specific heat (J/g at 20 oC) 1.910-1.916 1.900-1.911
Saponification number 188-192 168-181
Iodine value 110-126 97-108
Abbreviations: HEAR – High-Erucic Acid Rapeseed oil.
3.7.3 Saponification number
The saponification number is defined as the weight of potassium hydroxide, in
milligrams, needed to saponify one gram of fat. This parameter is inversely
proportional to the molecular weight of the fat. In other words, the higher the
molecular weight the lower is the saponification value. Replacement of long-chain
fatty acids such as erucic acid in rapeseed oil by C18 fatty acids increases the
saponification numbers from 168-181 to 188-192 due to the reduction in molecular
weight (Table 3.10).
3.7.4 Iodine Value
The iodine value (IV) indicates the degree of unsaturation of a fat or oil. It is defined
as the number of grams of iodine absorbed by 100 grams of fat. The higher value for
canola oil is due in part to the replacement of erucic acid with unsaturated C18 acids,
mainly oleic acid, together with a slight increase in the contribution of linoleic and
linolenic acids (Table 3.11).
The iodine value can also be calculated from fatty acid composition using specific
factors for each unsaturated fatty acid. It is claimed that this method provides more
accurate data.
30
3.8 SUNFLOWER OIL
The sunflower is the fourth largest oil source in the world, after soybean, palm, and
canola (edible rapeseed). Demand for sunflower oil increased sharply in the mid-
eighties when high polyunsaturated fatty acid (PUFA) margarine became the desired
table margarine for health reasons. The demand for this commodity has fallen since
then, and today sunflower oil faces tough competition, due to declining oil prices and
competition from the other regional crops. Soybean has taken away acreage from
sunflower in the US. In Europe, there is a shift toward canola production for biodiesel.
Table 3.11: World production and disappearance of sunflower oil (in 1000 tonnes
for crop year 1996/97-2000/01
Crop year* 2000/01 1999/00 1998/99 1997/98 1996/97
Opening Stock 1124 949 871 971 1155
Production 8867 9567 9281 8444 9111
Imports 2393 2696 2998 3048 3203
Exports 2370 2729 3033 2997 3280
Disappearance 9175 9360 9168 8594 9217
Ending Stock 838 1124 949 871 971
* Crop year is counted from October to September
3.8.1 Composition of Sunflower Oil
In addition to oil and protein, sunflower contains a number of micro constituents.
These include tocopherols, sterols and sterol-esters, phospholipids, waxes,
carotenoids, chlorophyll, and trace metals. Tocopherols are natural antioxidants.
Sunflower oil is high in α-tocopherol which makes the oil resistant to photo-
oxidation. -Tocopherol, which provides oxidative stability against autoxidation, is
present in sunflower oil only at low levels.
3.9 SUNFLOWER OIL REFINING
Crude sunflower oil is refined, bleached, winterized (dewaxed), and deodorized
before being used for edible purpose. The crude oil contains several impurities that
must be reduced in order to make the oil suitable for food application. There are two
groups of impurities present in the crude sunflower oil:
Macro impurities which can be measured in percentage of the crude oil
Micro impurities that are present in small amounts, generally at ppm or even
ppb levels
31
Although they are present in minute quantities, the presence or absence of some of
the micro impurities can have very significant effect on the stability of the oil.
Refining can be done in both batch and continuous processes. The batch process is
used for small quantities of oil and has been virtually eliminated from the developed
countries.
Crude oil is generally stored in large tanks with capacities up to a few thousand
tones depending upon the size of the refinery. These tanks have optional heating
coils but most of them do not have mechanical agitation. Agitation is beneficial
because wax, phospholipids, and moisture tend to settle to the bottom of the tank
and this may cause increased refining losses. Crude sunflower oil specifications are
shown below. This is set by Rule 14 of the American Fats and Oils, a trade
organization in the US.
Table 3.12: Specifications of Crude Sunflower Oil
Item Value
Flash point (oC) 121 minimum
Halpen test Negative
Saponification value 188-194
Unsaponifiables 1.3% maximum
Free fatty acids (as oleic acid) 2.0% maximum
Moisture and volatile 0.5% maximum
Insoluble impurities 0.3% maximum
Lovibond red color 2.5 maximum
Linolenic acid 1.0% maximum
The above specifications refer to macro components.
3.10 PHYSICAL REFINING PROCESS
In physical refining, the crude oil is first degummed by treating it with citric acid.
This converts most of the non-hydratable phospholipids to a hydratable type which
are removed from the crude oil in a centrifuge. The oil is then treated with acid
activated bleaching clay at 120-130oC under an absolute pressure (<50 mm of
mercury) using a vacuum ejector or a vacuum pump, and mechanically agitating the
oil with bleaching clay for 30-45 min. The bleaching clay is separated from the oil in a
plate and frame or a pressure leaf filter.
The oil should be kept out of contact with air during filtration to prevent oxidation of
the oil. The hot oil can be sent to a hydrogenation reactor or directly to product
formulation when hydrogenation is not required. For dewaxing, the oil is cooled and
taken through the dewaxing process. Finally the oil is refined deodorization. In this
process, the oil is steam-distilled under an absolute pressure of 3-6 mm of mercury
32
and at a temperature of 235-245°C in a batch, semi-continuous, or continuous
deodorizer. The deodorized oil is rapidly cooled to < 150°C under vacuum and 50
ppm of citric acid is added to chelate any traces of metal.
The oil is further cooled in external coolers to a temperature of 5oC above the melting
point of the product if solid. If it is liquid, it should be cooled down to < 35°C. In all
cases, the oil is saturated with nitrogen gas as it leaves the deodorizer and stored in
nitrogen-blanketed tanks to protect the oil from oxidation. Physical refining can be
effective only if the non-hydratable phospholipid level in the crude oil is low. This
requires that neither the seeds nor the crude oil have been abused.
Such oils tend to have a higher level of non-hydratable phospholipids which can
cause some difficulty in dewaxing and hydrogenation, and may also make it difficult
to reduce the free fatty acid level in the deodorized oil to less than 0.05%.
3.11 CHEMICAL REFINING PROCESS
In the US, sunflower oil is refined by the Alfa Laval's long mix continuous oil
refining process. Although it is better to degum the oil prior to refining, this
procedure is not generally followed in the US, because the Alfa Laval long mix
process removes the phospholipids from the oil quite effectively without prior
degumming of the crude oil In this process, the crude oil is mixed with a solution of
sodium hydroxide through a high shear mixer at 27-30°C and then passed through a
specially designed retention mixer to allow the sodium hydroxide to convert the
non-hydratable phospholipids to a more hydratable form.
This generally takes 3 min of residence time in a special retention mixer but a
retention time up to 6min does not hurt the oil. Typically, a 12-14 Degree Baume
caustic solution is used for refining crude sunflower oil. A higher strength of caustic
is not needed, unless the oil is high in non-hydratable phospholipids or very dark in
color.
The refined oil leaving the primary centrifuge contains 0.01-0.02% free fatty acid and
100-500 ppm of soap" and the latter must be removed. The refined oil is mixed with
deionized water (10-15'% of the oil flow), heated to 85° to 90°C, mixed, and then
centrifuged to separate the water from the oil. The purpose of washing with water is to
remove the soap from the refined oil. The water-washed oil contains 0.02-0.03% free
fatty acid and 10-50ppm of soap. The phosphorus content of the refined and water-
washed oil is 5 ppm or less. Nearly 90% of the phospholipids of the original crude oil is
removed in the refining and water-washing steps. In contrast to the physical refining
process, this method is capable of refining crude sunflower oil containing a high level
of non-hydratable phospholipids, and still producing a lower phosphorus content in
the refined oil.
The water-washed oil is bleached in the same manner as described under physical
refining. It is recommended that a very low dosage of hydrated silica (Trysil or
33
similar ingredients), a small amount of citric acid (50ppm, oil basis) and acid-
activated bleaching clay is applied for a more complete removal of phosphorus, trace
metals, and any products of oil oxidation that might remain from the crude oil stage.
To obtain the best results the manufacturer of Trysil recommends removal of
hydrated silica by filtration and further bleaching after addition of citric acid and
bleaching clay. The bleached oil shows the following analyses.
Table 3.13: Properties of bleached sunflower oil
Analysis Value
Free fatty acid 0.03-0.06%
Soap 0
Phosphorus <1 ppm
Iron <0.5ppm
Calcium <0.2ppm
Magnesium <0.2ppm
Chlorophyll <30ppb
There is usually less of a concern about the red color at this stage because removal of
phosphorus, trace metals, and soap are of prime importance and the red color is
reduced later in the deodorizer.
The oil is deodorized under the same conditions as in physical refining except that in
the latter, the deodorizer is designed to handle a much larger volume of fatty acids
and therefore has a few extra design features compared to the chemical refining
process. The typical analysis for deodorized sunflower oil is shown below:
Table 3.14: Properties of deodorized Sunflower Oil
Analysis Value
Free fatty acid* 0.03-0.01%
Soap 0
Phosphorus <1 ppm
Iron <0.5ppm
Calcium <0.2ppm
Magnesium <0.2ppm
Chlorophyll <30ppb
Lovibond red color <1.5 (general industry standard) >24
for well dewaxed oil
Wax content in well dewaxed oil <15 ppm
34
Crude cottonseed oil, derived mainly from the seeds of Gossypium hirsutum
(American) or Gossypium barbadense (Egyptian) varieties of cotton, has a strong,
characteristic flavor and a dark, reddish-brown color from the presence of highly
colored material extracted from the seed. It is a member of a particularly useful
group of vegetable oils, whose fatty acids consist substantially of C16 and C18 fatty
acids containing no more than two double bonds.
Genetic engineering has been applied to a number of oilseed plants, including cotton,
to alter the fatty acid profile. Generally, it has been found that fatty acid composition
can be changed to improve functionality or for nutritional reasons. To improve
oxidative and frying stability, the primary thrust of research has been to increase the
level of oleic acid at the expense of the polyunsaturated acids particularly
responsible for oxidation and polymerization. To enhance functionality and
plasticity, emphasis has been on increasing the level of saturated acids such as
palmitic and/or stearic. Such oils
then do not need to undergo
partial hydrogenation, which
produces the trans isomers now
believed to be nutritionally
undesirable. Oils with reduced
content of saturated acids have
also been developed. This
permits a ‘lower-saturated’ claim
to be put on the label.
Figure 3.4: Cottonseed Oil
Source: www.saranabugroup.com
Generally, it appears that genetic engineering may enable the farmer to grow
functional oils superior to those obtained by traditional blending and processing
techniques. Howe there are Iimiting factors to this improved technology,
particularly Identity Preservation (IP) and economics. IP requires segregated fields,
Storage, handling, transportation of seed and of oil, and seed extraction. Existing
systems are designed mainly to handle very large quantities of commodity oilseeds.
IP is only one of the factors contributing to the final cost of the premium product –
a cost which end – users have proved reluctant to accept. Success has come where
the modified product has displaced the earlier from and itself become the
commodity product as with rapeseed/canola oil.
Despite the difficulties, Australian scientists have developed improved cottonseed
oils with enhanced levels of oleic (20% raised to 77% mainly at the expense of
linoleic acid) and of stearic acid (2% raised to 38% at the expense of both oleic and
linoleic acid)
35
Cottonseed oil nonglyceride components
The primary constituents in crude vegetable oils (the triacylglycerols) are
accompanied by varying amounts of nonglyceride materials. Cottonseed oil is
unusual for the amount and variety of such substances present in the crude oil.
The content of nonglyceride substances, exclusive of free fatty acids, commonly
only amounts to 2% or more in the crude oil. These minor components also
referred to as the unsaponifiable fraction, consist of phospholipids, tocopherols,
sterol, resins, carbohydrates, pesticide. and gossypol and other pigments.
Physical Properties of Cottonseed Oil
The physical properties of all fats and oils" including cottonseed oil, are determined
by their chemical composition. Physical characteristics are of practical importance
because most applications depend on the melting behavior, solubility, flavor,
density, appearance and on other physical properties to provide functionality in
finished products.
Melting Point
The temperature range at which cottonseed oil changes from a solid to a liquid is 50-
60°F.
Cloud Point
Cottonseed oil that has not been winterized or hydrogenated will have a cloud point
of 30-38°F (-1.10C - 3.30C).
Pour Point
The pour point another ‘melting point' determination, of an oil is the temperature at
which it just remains pourable. For crude cottonseed oil, the pour point is between 25
and 32°F. The pour point temperature rises as the oil is saturated: for hydrogenated
cottonseed the poor point will be higher than for the unhardened oil and can be as
high as 140°F (60°C) depending upon the degree of saturation.
Refining
Two different refining systems are currently used for vegetable oils: chemical and
physical refining. Some shortcomings experienced with physical refining have
maintained alkali-refining as the preferred vegetable oil purification technique in the
US (Hamm 200). Some oils, like cottonseed, contain non-glyceride materials that
cannot be removed adequately by physical refining, However gossypol and related
pigments in cottonseed oil readily combine with caustic soda and are thus removed
more effectively by alkali-refining.
36
Bleaching
The usual method of bleaching is by adsorption of the pigments and other
nonglyceride impurities on bleaching earth. In a typical process, the bleaching
materials are added to the oil in an agitated vessel either at atmospheric pressure or
under a vacuum. The oil is heated to a bleaching temperature of 160-230°F (70-110°C)
and held to allow contact time with the bleaching earth. After the adsorbent has
captured the impurities it is removed from the oil with a filtration system.
Fractionation
Cottonseed oil has melting points spanning a range from. -13.3° to 35°C (8° to 95°F)
due to its triacylglycerol composition. This range of melting points: limits the
applications for cottonseed oil Application potential can be increase with
fractionation, a process by which oil is separated into two or more portions, The
three commercial processes used commercially for the fractionation of edible fats and
oils are: dry fractionation, solvent fractionation, and aqueous detergent fractionation.
Dry fractionation, which includes winterization, dewaxing, hydraulic pressing, and
crystal fractionation processes, is probability the most widely used method. Solvent
or aqueous, detergent fractionation processes provide better separation of specific
fractions for the, more sophisticated fats and oils products.
Post-Bleaching
A separate bleaching operation for oils that have been hydrogenated, fractionated or
interesterified has three purposes. It removes all traces of any catalyst used in die
preceding process, any undesirable colours generated by the preceding process, and
any peroxide and secondary oxidation products, Post-bleach systems are usually
batch systems to enable them to accommodate a wide variety of product.
De-Odorization
Edible fats and oils retain undesirable flavors and odors, after refining and develop
other undesirable organoleptic properties during bleaching, hydrogenation,
fractionation and interesterification. Deodorization is a vacuum-steam distillation
process operated at elevated temperatures to remove free fatty acids and other
volatile odoriferous components that cause the undesirable flavors and odors.
Additional deodorization benefits include heat-bleaching to destroy carotenoid
pigments, pesticide removal, and reduction of cyclopropenoid fatty acids to a
negligible, level, all of which ensure oil purity.
The odoriferous substances in oils are free fatty acids, peroxides, aldehydes, alcohols
and other organic compounds. Experience has shown that the flavor and odor
removal correlates well with the reduction of free fatty acids. Therefore, all
commercial deodorization consists of steam, stripping the oil for free fatty acid
removal. Currently, batch. semi-continuous, and continuous systems of various
designs are utilized to produce deodorized oils.
37
Utilization of Cottonseed Oil
Cooking Oil / Salad Oil / Margarine
High Stability Oils
These edible oils that, are clear at room temperature and also possess exceptional
oxidative and flavor stability. High stability oils will withstand the abuse during AOM
testing for periods in excess of 75 h and some longer than 300 h, as opposed to a 15 h
ADM result for cottonseed cooking oils. High stability oils can be produced by partial
hydrogenation followed by fractionation or by genetic engineering of the oilseed.
3.13 NON-EDIBLE VEGETABLE OILS
Continuous and large-scale production of biodiesel from edible oils has recently been
of great concern because they compete with food materials - the food versus fuel
dispute. There are concerns that biodiesel feedstock may compete with food supply
in the long-term. Hence, use of non-edible vegetable oils when compared with edible
oils is very significant in developing countries because of the tremendous demand
for edible oils as food, and they are far too expensive to be used as fuel at present.
The production of biodiesel from different non-edible oilseed crops has been
extensively investigated over the last few years.
Some of these non-edible oilseed crops include jatropha tree (Jatropha curcas), karanja
(Pongamia pinnata), tobacco seed (Nicotiana tabacum L.), rice bran, mahua (Madhuca
indica), neem (Azadirachta indica), rubber seed tree (Hevea brasiliensis), and
microalgae. Algae contain anywhere between 2% and 40% of lipids/oils by weight.
3.14 JATROPHA OIL
Jatropha Curcas
Jatropha oil is derived from the plant Jatropha Curcas, a member of the
Euphorbiaceae family. It is a tall bush/small tree
up to 6 m in height, native to Central America,
and was probably distributed by Portuguese
seafarers via the Cape Verde Islands and former
Portuguese Guinea (now Guinea Bissau) to other
countries in Africa and Asia.
The oil-bearing seeds of Jatropha Curcas are toxic
and therefore unfit for human and animal
consumption. Their toxicity arises from the presence
of lectin, saponin, carcinogenic phorbol, and a
trypsin inhibitor. The seeds of this genus are also a
source of the highly poisonous toxalbumin curcin.
Figure 3.5: A typical Jatropha shrub
Source: valuablecrops.com
38
On an average, the seeds contain about 35% of non-edible oil (with regional
variations on account of agro-climatic conditions). This oil can be used for
manufacture of candles and soap, in the cosmetics industry, for cooking and lighting
by itself or most importantly, as a diesel/paraffin substitute. Being a hardy species, it
is planted as a hedge (living fence) by farmers all over the world around homesteads,
gardens and fields. It is not browsed by animals and requires very little water.
Properties of Jatropha Oil
Oil is obtained from Jatropha seeds largely by the process of crushing/expelling, or
through solvent extraction. The following table presents an overview of the physio-
chemical properties of Jatropha Oil.
Table 3.15: Summary of Statistical Analysis of Test Properties of Jatropha Samples
Properties Mean Standard
Deviation Repeatability Test Method/s
Viscosity 35.3600 0.7408 0.35% of Mean value ASTMD445, IS 1448~ P25
Calorific Value 39.4299 0.3481 within 66 cal/g IS 1448~ P6
Density 0.9193 0.0012 within 0.001 ASTM D 4052. IS 1448~ P32
Flash point 214.1778 18.0401 within50C ASTM D 93, IS 1448~ P21
Add Numbu 10.4833 3.0016 - ASTM D 974, IS 1448; PI
Ash Content 0.0234 0.0096 -- IS 15607, ISO 6245, IS 1448~
Water Content 0.0200 0.0170 within 2% of Mean value IS 1448~ P40, ASTM D 2707
Carbon Residue 0.3581 0.1875 - ASTM D 4530
Iodine Number 101.1111 4.4001 - ASTMD5678
Saponification Number 198:4444 4.3333 +/-2 IS 1448; P55
Su1fur Content 20.2222 6.2605 3.4% of Mean value ASTM D 5453, IS 1448~ P83
Cloud Point 1.5556 3.1269 exceed 211'C in 1 case in 20 ASTM D 2500
Specific Heat 23889 0.2155 - ASTME 1269
Thermal conductivity 32.4633 05561 +1-10% of Mean. value ASTMD2717
Surface Tension 0.2331 0.0508 ASTMD3825
Oxidation Stability 3.2056 2.4755 EN 14112
3.15 WASTE COOKING OIL AS BIODIESEL FEEDSTOCK
Waste cooking oil (WCO) is a promising alternative to vegetable oil for biodiesel
production. In order to reduce the cost of production, WCO would be a good choice
as raw material since it is cheaper than virgin vegetable oils30. Its price is 2-3 times
cheaper than virgin vegetable oils31. The conversion of WCO into methyl esters
30. Ziejewski M, et al., Diesel engine evaluation of a nonionic sunflower oil–aqueous ethanol microemulsion. J Am Oil Chem
Soc 1984;61:1620–6. 31. Abdullah AZ et al., Critical technical areas for future improvement in biodiesel technologies. Environ Res Lett 2007;2: 1–6.
39
through the trans-esterification process approximately reduces the molecular weight
to one-third, reduces the viscosity by about one-seventh, reduces the flash point
slightly and increases the volatility marginally, and reduces pour point
considerably32. The production of biodiesel from WCO is challenging due to the
presence of undesirable components such as FFAs and water33.
3.16 ANIMAL FATS AS BIODIESEL FEEDSTOCK
Another group of feedstock for biodiesel production is fats derived from animals.
Animal fats used to produce biodiesel include tallow, choice white grease or lard,
chicken fat and yellow grease. Compared to plant crops, these fats frequently offer an
economic advantage because they are often priced favorably for conversion into
biodiesel Animal fat methyl ester has some advantages such as high cetane number,
non-corrosive, clean and renewable properties. Animal fats tend to be low in FFAs
and water, but there is a limited amount of these oils available, meaning these would
never be able to meet the fuel needs of the world.
3.17 ALGAE-BASED BIOFUELS
Tiny, slimy algae could be a viable form of fuel for everything from jets to diesel
generators and power a new industry, research scientists said. Nova Scotia research
council will test the creation of biofuels from the unicellular organism. It could help
ignite a provincial energy industry. The algae - a microscopic version of the green
slime that fouls pools and fish tanks-could become huge pools of absorption for carbon
dioxide. And the chemical reaction of the carbon dioxide, water and organisms
produces oxygen, sugars, proteins and plant oils that can be used in engines.
Biofuels made from algae have the potential to
deliver clean air, clean energy, clean water and
also have clear economic benefits. Algae is
already being used to produce biodiesel fuels in
North America, but researchers at the National
Research Council see wider applications in
provinces like Nova Scotia that rely heavily on
coal-fired electricity plants.
Figure 3.6: A modern algal biomass cultivator
Source: www.treehugger.com
Carbon 2 Algae Inc. expects a future where smokestacks from coal-burning power
plants could infuse their carbon dioxide into huge containers of the hungry micro-
organisms.
32. Ma F, Hanna MA. Biodiesel production: a review. Bioresour Technol 1999;70:1–15 33. Demirbas A. Biodiesel from wood oils in compressed methanol. Energy Source Part A 2009;31:1530–6
40
CCoonnvveerrssiioonn tteecchhnnoollooggiieess ttoo mmaakkee BBiiooddiieesseell
With the increase in the price of the petroleum and the environmental concerns about
pollution, biodiesel is becoming a developing area of high concern. One of the advantages of
this fuel is that the raw materials used to produce it are natural and renewable. All these
types of oils come from vegetables or animal fat, making it biodegradable and nontoxic.
Different technologies for production, with different kinds of raw materials are in various
stages of applications and developments such as commercial, semi-commercial, design
stage, pilot scale, lab scale, or research stage.
Out of the various processes for biodiesel manufacture, trans-esterification is one of the most
important current technologies.
The other two processes of relatively little importance are,
Pyrolysis And Cracking and
Micro-emulsification
Biodiesel from trans-esterification of the vegetable oils is better than diesel fuel in terms of
sulfur content, flash point, aromatic content and biodegrability. The other typical ways of
production by pyrolysis, microemulsification are so far non competitive with trans-
esterification.
Trans-esterification is the reversible reaction of a fat or oil with an alcohol (methanol or
ethanol) to form fatty acid alkyl esters and glycerol. Fatty acid methyl ester (FAME) is
commonly known as biodiesel. Also known as methanolysis, this reaction is well studied
and established using acids or alkalis as catalysts13.
The reaction proceeds with catalyst or without any catalyst by using primary or secondary
monohydric aliphatic alcohols having 1–8 carbon atoms. Alcohols employed in the trans-
esterification are generally short chain alcohols such as methanol, ethanol, propanol, and
butanol.
Trans-esterification reaction is an equilibrium reaction. In this reaction, however, a larger
amount of methanol is used to shift reaction equilibrium to right side and produce more
methyl esters as proposed product.
Ethanol is good in trans-esterification reaction because it is derived from agricultural
products, is renewable and biologically less objectionable in the environment. However,
methanol is preferred because of its low cost and its physical and chemical advantages being
polar shortest chain alcohol13.
Reaction in the trans-esterification of a triglyceride is shown in figure 4.1. Biodiesel is the
main product with glycerol as byproduct.
CCHHAAPPTTEERR 44
41
Figure 4.1: Trans-esterification of a triglyceride
Source: Abdullah et al., Critical technical areas for future improvement in biodiesel technologies.
Environ Res Lett 2007; 2: 1–6.
Details of various processes available for production of Biodiesel and their reviews are
discussed in sections 4.1 to 4.19. These sections discuss the major aspects briefly. The details
can be consulted from the references and the corresponding Annexures.
4.1 TRANS-ESTERIFICATION OF TRIGLYCERIDES TO BIODIESEL
The catalytic trans-esterification of vegetable oils with methanol is an important
industrial method used in biodiesel synthesis. The reaction of trans-esterification can
be catalysed by various types of catalysts.
The reaction rates and various other parameters and characteristics of feed and
products may have to be considered accordingly. As seen in the literature this
reaction is well studied and established using acids or alkalis, such as sulfuric acid or
sodium hydroxide as catalysts.
However, acidic catalytic systems are less active or completely inactive for long chain
alcohols. Trans-esterification using acid catalysts is much slower than that obtained
from alkali catalysis. If high contents of water and FFAs are present in the vegetable
oil, acid-catalyzed trans-esterification can be used
Usually, industries use sodium or potassium hydroxide or sodium or potassium
methoxide as catalyst, since they are relatively cheap and quite active for this
reaction. Alkaline catalysts have the advantages, e.g. short reaction time and
relatively low temperature can be used with only a small amount for catalyst and
with little or no darkening of colour of the oil. They show high performance
However, alkaline catalyzed trans-esterification has several drawbacks: it is energy
intensive, the recovery of glycerol is difficult, the catalyst has to be removed from the
42
product, alkaline wastewater requires treatment, and FFAs and water interfere with
the reaction
Enzymatic catalysts like lipases are able to effectively catalyze the trans-esterification
of triglycerides in either aqueous or non-aqueous systems. In particular, it should be
noted that the byproduct, glycerol, can be easily recovered with simple separation
processes.
Enzymes-catalyzed procedures, do not produce side reactions, but the lipases are
very expensive for industrial scale production and a three-step process was required
to achieve a 95% conversion. So recycling and reusing them is often a must for
commercial viability
Recently, there have been some reports on the non-catalytic trans-esterification
reaction employing supercritical methanol conditions. Trans-esterification of
vegetable oils in supercritical methanol are carried out without using any catalyst.
Supercritical methanol has a high potential for trans-esterification of triglycerides.
Mustafa Balat et al13 show various types of catalysts, feed-stocks, operating
conditions to maximize the production of biodiesel Pretreatment of the feed needs to
be carried out to conduct the trans-esterification reactions.
Typical reaction conditions for biodiesel synthesis using homogeneous alkali
catalysis are shown in the following table
Table 4.1: Reaction conditions for biodiesel synthesis using homogeneous alkali catalysis
Feedstock Triglyceride mixtures with low free fatty acid
contents (<0.5%) e.g., refined vegetable oils +
anhydrous short chain alcohol (generally, methanol)
Alcohol-to-oil molar ratio
(recommended)
6:1
Temperature 333–338 K
Pressure 1.4–4.1 bar
Catalyst NaOH (most common)
Catalyst concentration (by
Weight of lipid feedstock)
0.5–2 wt.%
Conversions >95% can be expected after 1 h reaction
The reactions take place at low temperatures (338 K) and at modest pressures of 2
atm, Biodiesel is further purified by washing and evaporation to remove any
remaining methanol. The oil (87%), alcohol (9%), and catalyst (1%) are the inputs in
the production of biodiesel (86%), the main output. For a complete reaction, an FFA
value of lower than 3% is needed and the other materials should be substantially
anhydrous. Ideally the presence of water gives rise to hydrolysis of some of the
produced ester, with consequent soap formation. Soap formation reduces catalyst
efficiency, causes an increase in viscosity, leads to gel formation and makes the
separation of glycerol difficult.
43
Pretreatment is not required if the reaction is carried out under high pressure (9000
kPa) and high temperature (513 K), where simultaneous esterification and trans-
esterification take place with maximum yield obtained at temperatures ranging from
333 to 353 K at a molar ratio of 6:1.
Typical utility inputs and mass requirements for the trans-esterification process are
given in Table of the annexure 313, reproduced below.
Table 4.2: Inputs and mass requirements for the trans-esterification process
Input Requirement /ton
biodiesel
Feedstock 1000 kg vegetable oil
Steam requirement 415 kg
Electricity 12 kWh
Methanol 96 kg
Catalyst 5 kg
Hydrochloric acid (37%) 10 kg
Caustic soda (50%) 1.5 kg
Nitrogen 1 Nm3
Process water 20 kg
4.2 NOVEL HIGHLY INTEGRATED BIODIESEL PRODUCTION
TECHNOLOGY IN A CENTRIFUGAL CONTACTOR SEPARATOR
DEVICE34
The base catalyzed production of biodiesel (FAME) from sunflower oil and methanol
in a continuous centrifugal contactor separator (CCS) with integrated reaction and
phase separation was studied by G. Kraai et al.
Study looks into the possibilities for the development of modified reaction
equipments for continuous production of bio diesel and its purification.
The effect of catalyst loading (sodium methoxide), temperature, rotational frequency
and flow rates of the feed streams was also investigated.
An optimized and reproducible FAME yield of 96% was achieved at a feed rate of
12.6mLmin−1 sunflower oil and a sixfold molar excess of MeOH (3.15mLmin−1)
containing the catalyst (1 wt% with respect to the oil).
A jacket temperature of 75OC and a rotational frequency of 30 Hz were applied. The
productivity under those conditions (61 kg FAME m−3 liquid min−1) was slightly
higher than for a conventional batch process. The main advantage is the combined
reaction–separation in the CCS, eliminating the necessity of a subsequent liquid–
liquid separation step.
34. Kraai et al., Novel highly integrated biodiesel production technology in a centrifugal contactor separator device, 2009
(Annexure 3)
44
The study provides the proof of principle for the continuous biodiesel manufacture
in a highly integrated CCS of the type CINC V02.
As such, it demonstrates the potential of CCS equipment to be used for combined
reactions and separation for biphasic (catalytic) systems.
At optimum conditions a reproducible FAME yield of 96% was achieved.
The volumetric production rates are at least comparable to state of the art batch
processes.
Further improvements are likely by hardware modifications, and particularly by
modifications of the annular zone to allow for higher flow rates while maintaining a
high conversion level.
Due to the compact size and flexibility in operation, the CCS equipment is likely very
suitable for biodiesel production in mobile units in developing countries.
A cascade of two CINCs in series, one for biodiesel production and one for a
subsequent aqueous wash to remove remaining glycerol and catalyst, followed by a
methanol stripper, may be a very attractive process option for further exploration
and demonstration.
4.3 BIODIESEL PRODUCTION PROCESS OPTIMIZATION AND
CHARACTERIZATION TO ASSESS THE SUITABILITY OF THE
PRODUCT FOR VARIED ENVIRONMENTAL CONDITIONS35
In this study conducted by T. Evera et al (Annexure 4), both edible (coconut oil, palm
oil, groundnut oil, and rice bran oil) and non-edible oils (pongamia, neem and cotton
seed oil) were used to optimize the biodiesel production process variables like
catalyst concentration, amount of methanol required for reaction, reaction time and
reaction temperature. The fuel properties like specific gravity, moisture content,
refractive index, acid value, iodine number, saponification value and peroxide value
were estimated. Based on the cetane number and iodine value, the methyl esters
obtained from palm and coconut oils were not suitable to use as biodiesel in cold
weather conditions, but for hot climate condition biodiesel obtained from the
remaining oil sources is suitable.
The study on the biodiesel production process optimization of edible and non-edible
oils showed that the quantity of catalyst, amount of methanol, reaction temperature
and reaction time are the main factors affecting the production of methyl esters.
Some of the typical figures based on the study are reproduced below:
35.
T. Eevera, et al., Biodiesel production process optimization and characterization to assess the suitability of the product for varied environmental conditions, Renewable Energy, 2009 (Annexure 4)
45
Figure 4.2: Effect of Catalyst concentration on Methyl Ester yield
Figure 4.3: Effect of reaction time on Methyl Ester yield
46
Figure 4.4: Effect of Methanol concentration on Methyl Ester yield
Figure 4.5: Effect of reaction temperature on Methyl Ester yield
The optimal values of parameters for achieving maximum conversion of oil to esters
depended on the chemical and physical properties of feed stocks.
The following conclusions are drawn from the study:
Addition of excess catalyst causes more triglycerides’ participation in the
saponification reaction leading to a marked reduction in the ester yield.
47
Biodiesel production process is incomplete when the methanol amount is less
than the optimal value. Operating beyond the optimal value, the ester yield
would not be increased but will result in additional cost for methanol recovery.
Higher reaction temperature decreases the viscosities of the oils and resulted in
increased rate of trans-esterification and shortening of the reaction time. When
the temperature increases beyond the optimum level it induces a negative impact
on the ester yield due to acceleration of the saponification of triglycerides.
Sufficient reaction time should be allowed to ensure complete conversion of
triglycerides into esters. However, excess reaction time did not promote the
conversion but favors the reverse reaction of trans-esterification which resulted in
a reduction in the ester yield.
The optimal reaction conditions for production of methyl esters from edible oil
sources are established as follows: the reaction time of 90 min at 50OC, 180 ml of
methanol for 1000 ml of oil and 1.5 wt.% of NaOH catalyst. For non-edible oil
based methyl esters’ production except the amount of methanol (210 ml/1000 ml
of oil) requirement, the remaining optimal parameters are similar to edible oil
based methyl esters’ production.
4.4 REVIEW ON ACTIVITY OF SOLID HETEROGENEOUS CATALYSTS
AND NANOCATALYSTS FOR BIODIESEL PRODUCTION36
4.4.1 Solid Heterogeneous Catalysts
Performance of some of the homogenous catalysts have been discussed above.
Heterogeneous catalysts are promising for the trans-esterification reaction of
vegetable oils to produce biodiesel. Unlike homogeneous, heterogeneous catalysts
are environmentally benign and could be operated in continuous processes.
Moreover they can be reused and regenerated. However a high molar ratio of alcohol
to oil, large amount of catalyst, high temperature and pressure are required when
utilizing heterogeneous catalyst to produce biodiesel.
In this paper by Masoud Zabeti et al, the catalytic activity of several solid base and
acid catalysts, particularly metal oxides and supported metal oxides, was reviewed.
Solid acid catalysts were able to do trans-esterification and esterification reactions
simultaneously and convert oils with high amount of FFA (Free Fatty Acids).
However, the reaction rate in the presence of solid base catalysts was faster. The
catalyst efficiency depended on several factors including its physic-chemical
properties. Effective factors on catalytic activity of solid catalysts are specific surface
area, pore size, pore volume and active site concentration on the surface of catalyst.
Moreover type of precursor of active materials has significant effect on the catalyst
activity of supported catalysts. However, active site concentration was found to be
the most important factor for solid catalyst performance.
36.
Masoud Zabeti, et al., Activity of solid catalysts for biodiesel production: A review, Fuel Processing Technology, 2009 (Annexure 5)
48
The use of catalyst supports such as alumina, silica and zinc oxide could improve the
mass transfer limitation of the three phase reaction.
The amount of methyl ester yields and conversion of oils depend on not only catalyst
activity but also the type of oils and the applied operation conditions.
Furthermore, by anchoring metal oxides inside pores, catalyst supports could
prevent active phases from sintering in the reaction medium.
By modifying the catalyst activity and synthesis cost, heterogeneous catalyst could be
replaced by homogeneous catalyst for the biodiesel production. Summarization of
the activity of metal oxides and supported catalysts as heterogeneous catalysts for
biodiesel production is shown in the following table.
49
50
4.4.2 Heterogeneous Nanocatalytic Process for the Production of Biodiesel
The present invention relates to a process for the production of alkyl esters of
carboxylic acids for use as biodiesel starting from the reaction of trans-esterification
of triglycerides originating from oils and fats of vegetable or animal origin, which
can be used individually or in mixtures with one another in any proportions,
employing heterogeneous catalysis by means of protonated lamellar titanate
catalysts in nanostructured form, and said forms can comprise, among in other
forms, nanotubes, nanofibres or nanosheets. Nano form makes them very active
catalysts.
4.5 A REVIEW ON BIODIESEL PRODUCTION THROUGH THE USE OF
DIFFERENT SOURCES AND CHARACTERIZATION OF OILS AND
THEIR ESTERS AS THE SUBSTITUTE OF DIESEL11
Lot of researchers focused mainly the edible oils to produce the Biodiesel because of
easily availability and familiarity. Some of the results have been discussed already.
Few researchers concentrated on Non edible oil for the same purpose. The authors
referenced presented a table stated below showing various types of oil for biodiesel
production:
Table 4.3: Types of oil for biodiesel production
Vegetable oils Non-edible oils Animal Fats Other Sources
Soybean Almonds Lard Bacteria
Rapeseed Abutilon muticum Tallow Algae
Canola Andiroba Poultry Fat Fungi
Safflower Babassu Fishoil Micro algae
Barley Brassica carinata Tarpenes
Coconut B. napus Latexes
Copra Camelina Cooking oil (Yellow
Grease)
Cotton seed Camaru Microalgae
(Chlorellavulgaris)
Groundnut Cynara cardunculus
Oat Jatrophacurcas
51
Vegetable oils Non-edible oils Animal Fats Other Sources
Rice Jatropha nana
Sorghum Jojoba oil
Wheat Pongamiaglabra
Winter rapeseed oil Laurel
Lesquerellafendleri
Mahua
Piqui
Palm
Karang
Tobacco seed
Rubber plant
Rice bran
Sesame
Salmon oil
Enzymatic processes using both extra cellular and intracellular lipases have recently
been developed. The cost of lipase production is the main hurdle to
commercialization of the lipase-catalyzed process; several attempts have been made
to develop cost-effective systems.
In terms of production cost, there also are two aspects, the trans-esterification process
and byproduct (glycerol) recovery. A continuous trans-esterification process is one
choice to lower the production cost. The foundations of this process are a shorter
reaction time and greater production capacity.
The recovery of high quality glycerol is another way to lower production cost. Land
may be a cost increasing factor for Biodiesel production, because of more and more
land required to live the growing population. To overcome the land problem, the
high yielding Biodiesel plants (non edible plants) should be grown in marginal and
waste land areas.
4.6 PROCESS INTENSIFICATION TECHNOLOGIES IN CONTINUOUS
BIODIESEL PRODUCTION37
Process intensification technologies have significant potential for enhancement of
biodiesel production. This contribution presents a brief review of some of
technologies being developed and includes description of some of the types of novel
reactors and relevant coupled reaction/separation processes.
These technologies enhance reaction rate, reduce molar ratio of alcohol to oil and
energy input by intensification of mass transfer and heat transfer and in situ product
separation, thus achieve continuous product in a scalable unit.
37. Zheyan Qiu, et al, Process intensification technologies in continuous biodiesel production, Chemical Engineering and
Processing: Process Intensification, 2010 (Annexure 6)
52
Some of these technologies have been commercialized successfully. Enhancement in
transport processes and higher reaction rates provide the scope for continuous
production. Hence higher conversion yields are possible, under milder conditions
and involving reduced molar ratios of alcohol to oil, lower reaction temperature and
catalyst concentration than conventional stirred reactors.
Some process intensification technologies offer the flexibility to process a variety of
feedstocks. Compared to conventional tank systems, these technologies are proved
more energy efficient because of enhanced heat transfer. Their small “footprint”
allows them to be scaled up easily and reduces the capital and operating cost and
thus increases profit.
The author has presented typical comparison of few of the parameters on process
intensification and their developmental status in the following table.
Table 4.4: Comparison of process intensification technologies for continuous biodiesel
production with conventional stirred tank reactors
Residence time Energy efficiency
(g/J)
Operating and capital
cost
Temperature control
Current status
Static mixer ~30 min 14.9-384 Low Good Lab scale
Micro-channel reactor 28s~several minutes
0.018 Low Good Lab scale
Oscillatory flow reactor
30 min N/A Low Good Pilot plant
Cavitational reactor Microseconds-several seconds
1x10-4to2x10-4 (hydrodynamic cavitation), 5x10-
6to2x10-5 (acoustic cavitation)
Low Good Commercial scale
Spanning tube in tube reactor
<1 min N/A Low Good Commercial scale
Microwave reactor Several minutes ~0.038L Low Good Lab scale
Membrane reactor 1-3h N/A Lower Easy Pilot plant
Reactive distillation Several minutes ~1.6z10-6 Lower Easy Pilot plant
Centrifugal contactor ~1 min N/A Lower Easy Commercial scale
4.7 A REVIEW ON BIODIESEL PRODUCTION USING CATALYZED
TRANS-ESTERIFICATION, REDUCTION OF UNDESIRABLE FFA AND
REFINEMENT OF BIODIESEL38
Today, most of the biodiesel is produced by the alkali-catalyzed process. Figure
shown below by the author Dennis Y.C. Leung et al is a simplified flow chart of the
alkali-catalyst process. As described earlier, feedstocks with high free fatty acid will
react undesirably with the alkali catalyst thereby forming soap.
38. Dennis Y.C. Leung, et al., A review on biodiesel production using catalyzed transesterification, Applied Energy, 2010
(Annexure 7)
53
The maximum amount of free fatty acids acceptable in an alkali-catalyzed system is
below 2.5 wt.% FFA. If the oil or fat feedstock has a FFA content over 2.5 wt.%, a
pretreatment step is necessary before the trans-esterification process.
Figure 4.6: Simplified process flow chart of alkali-catalyzed biodiesel production
All the steps as stated in the blocks are detailed in by the author.
For an alkali-catalyzed trans-esterification, the alkali catalyst that is used will react
with the FFA to form soap. Eq. below shows the saponification reaction of the
catalyst (sodium hydroxide) and the FFA, forming soap and water.
This reaction is undesirable because the soap lowers the yield of the biodiesel and
inhibits the separation of the esters from the glycerol.
In addition, it binds with the catalyst meaning that more catalyst will be needed and
hence the process will involve a higher cost.
Water, originated either from the oils and fats or formed during the saponification
reaction, retards the trans-esterification reaction through the hydrolysis reaction. It
54
can hydrolyze the triglycerides to diglycerides and forms more FFA. The typical
hydrolysis reaction is shown in Eq. below.
However, the FFA can react with alcohol to form ester (biodiesel) by an acid-
catalyzed esterification reaction. This reaction is very useful for handling oils or fats
with high FFA, as shown in the equation below:
Normally, the catalyst for this reaction is concentrated sulphuric acid. Due to the
slow reaction rate and the high methanol to oil molar ratio that is required, acid-
catalyzed esterification has not gained as much attention as the alkali-catalyzed
trans-esterification.
The main factors affecting the yield of biodiesel, i.e. alcohol quantity, reaction time,
reaction temperature and catalyst concentration are discussed.
For refining the crude biodiesel produced, the product should first be neutralized
and then put through an alcohol stripper before cleaning by either one of the
following approaches: water washing, membrane extraction, and dry washing.
A very promising method for washing biodiesel is the hollow fiber membrane
extraction, which effectively avoids emulsification during the washing step and
decreases the refining loss.
As a commercial fuel, the finished biodiesel must be analyzed using sophisticated
analytical equipment to ensure that it meets international standards even if it has
been stored for a long time
Because of its numerous industrial applications, the crude glycerol by product
should be refined with purity higher than 99% to make it usable
Other new processes of biodiesel production are described For instance, the Biox co-
solvent process converts triglycerides to esters through the selection of inert co-
solvents that generates a one-phase oil-rich system.
The non-catalytic supercritical methanol process is advantageous in terms of shorter
reaction time and lesser purification steps but requires high temperature and
pressure.
55
4.8 ONE-POT PROCESS COMBINING TRANS-ESTERIFICATION AND
SELECTIVE HYDROGENATION FOR BIODIESEL PRODUCTION FROM
STARTING MATERIAL OF HIGH DEGREE OF UNSATURATION39
A one-pot process combining trans-esterification and selective hydrogenation was
established to produce biodiesel from hemp (Cannabis sativa L.) seed oil which is
eliminated as a potential feedstock by a specification of iodine value (IV; 120 g I2/100
g maximum) contained in EN 14214.
A series of alkaline earth metal oxides and alkaline earth metal supported copper
oxide were prepared and tested as catalysts. SrO supported 10 wt.% CuO showed the
superior catalytic activity for trans-esterification with a biodiesel yield of 96% and
hydrogenation with a reduced iodine value of 113.
It also exhibited a promising selectivity for eliminating methyl linolenate and
increasing methyl oleate without rising methyl stearate in the selective
hydrogenation. The fuel properties of the selective hydrogenated methyl esters are
within biodiesel specifications. Furthermore, cetane numbers and iodine values were
well correlated with the compositions of the hydrogenated methyl esters according
to degrees of unsaturation.
This one-pot process gives opportunity to extend the high un-saturate materials for
biodiesel production, thus making a wide portfolio of raw materials available
without interfering with the food market.
4.9 CHEAPER EVER CAT FUELS PROCESS TO MANUFACTURE
BIODIESEL
The discussed catalytic process cuts the cost of biodiesel fuel.
Biodiesel fuel is being produced for under $2/gal from product wastes in a process
commercialized by Ever Cat Fuels (www.evercatfuels.com).
This is comparable to the cost of diesel fuel obtained from petroleum, says Arlin
Gyberg, a co-inventor of the process and a chemistry professor at Augsburg College,
Minneapolis.
Ever Cat, a new subsidiary of SarTec Corp. (www.sartec.com), has scaled up the
technology.
The plant uses a continuous process to produce 4-million gal/yr of fuel from two 6-ft
by 6-in.-dia reactors. The reaction takes about 6s, versus about 6h for a conventional
batch process, says Gyberg. The feed is a mixture of waste corn oil from bioethanol
plants and waste cooking oil, although about 40 feedstocks (animal fats and plant
oils) have been successfully pilot-tested.
39.
Ru Yang, et al., One-pot process combining transesterification and selective hydrogenation for biodiesel production from starting material of high degree of unsaturation, Bioresource Technology, 2010 (Annexure 8)
56
Preheated feed is introduced into the top of a catalyst-packed column and converted
Fatty acid removal polisher to biodiesel fuel under supercritical conditions at about
350°C and 200 psi. Conversion is practically 100%, since the process performs trans-
esterification of triglycérides and esteriñcation of free fatty acids. He notes
that conventional processes do trans-esterification, but convert fatty acids to soap.
Glycerol, an unwanted byproduct of traditional processing, is broken down in the
reactor and the small amount produced is recycled, along with alcohol.
Ever Cat has been using a zirconia catalyst particles since the plant started up. The
catalyst is not degraded by the process (hence; the name "Ever Cat").
If the column gets plugged, the catalyst can be heated to drive off the organics. The
company will likely switch to Titania catalyst developed by Rockwood Holdings
Inc.'s (Duisburg, Germany). Titania has worked as well in tests and its cost is a
fraction of that of zirconia. Ever Cat plans to scale up production to 30-million gal/yr
within two years by adding parallel reactors similar to those now in use.
Figure 4.7: Cheaper Ever Cat biodiesel manufacture process
4.10 BIODIESEL PRODUCTION FROM ACID OILS AND ETHANOL USING
A SOLID BASIC RESIN AS CATALYST40
As discussed earlier and by many other authors, conventional technology employs a
basic homogenous catalyst to perform the trans-esterification reaction. Normally
NaOH and methanol are used.
Other alternative catalyst which continues to be a homogeneous one is sulfuric acid.
It has the advantage of allowing the use of raw material with high amounts of free
fatty acids with the drawbacks that the reaction is much slower than with NaOH.
It has been compared the production of esters using sulfuric acid and a base solid
resin with ethanol anhydrous under similar operational conditions, such as T ¼ 55
40. J.M. Marchetti, et al., Biodiesel production from acid oils and ethanol using a solid basic resin as catalyst, Science direct,
2010 (Annexure 9)
57
degree C, initial amount of FFA ¼ 9.9% w/w, 2.2% w/w of each catalyst, 200 rpm of
agitation speed and a molar ratio of alcohol/mixture of 6.1:1.
Figure 4.8 shows that under the same operational conditions, sulfuric acid reaches its
final conversion in about 3 days time.
Figure 4.8: Variations of esters for both catalysts sulfuric acid (-) and
solid resin (∆).
However, this reaction time could be optimized in order to have a more competitive
process.
4.11 SUPERCRITICAL BIODIESEL PRODUCTION, POWER
COGENERATION: TECHNICAL AND ECONOMIC FEASIBILITIES41,42
An integrated supercritical fluid technology with power cogeneration to produce
biodiesel fuels, with no need for the costly separations involved with the
conventional technology, is proposed, documented for technical and economic
feasibility, and preliminarily designed.
The core of the integrated system consists of the trans-esterification of various
triglyceride sources (e.g., vegetable oils and animal fats) with supercritical
methanol/ethanol.
Part of the reaction products can be combusted by a diesel power generator
integrated in the system which, in turn, provides the power needed to pressurize the
41. A. Deshpande, G. Anitescu. Et al., Supercritical biodiesel production and power cogeneration: Technical and economic
feasibilities, Bioresource Technology, 2010 (Annexure 10) 42. Gleason; Rodney J., et al., Biodiesel Fuel And Method of Manufacture, 2009. US Patent Application 20090277077
(Annexure 11)
58
system and the heat of the exhaust gases necessary in the trans-esterification step.
The latter energy demand can also be satisfied by a fired heater, especially for higher
plant capacities. Different versions of this system can be implemented based on the
main target of the technology: biodiesel production or diesel engine applications,
including power generation.
The process options considered for biodiesel fuel production estimate break-even
processing costs of biodiesel as low as $0.26/gal $0.07/L) with a diesel power
generator and $0.35/gal ($0.09/L) with a fired heater for a plant capacity of 15,000
gal/day (56,775 L/day).
Both are significantly lower than the current processing costs of approximately
$0.51/gal ($0.13/L) of biodiesel produced by conventional catalytic methods. A retail
cost of biodiesel produced by the proposed method is likely to be competitive with
the prices of diesel fuels.
The authors have presented the Flow diagram for supercritical trans-esterification of
vegetable oils to biodiesel and a typical flow diagram for a conventional base
catalytic method to produce biodiesel. Both are presented below.
Figure 4.9: Flow diagram for supercritical trans-esterification of vegetable oils to biodiesel
59
Figure 4.10: Typical flow diagram for a conventional base catalytic method to produce
biodiesel
An economic analysis of the proposed SC process has been performed. It was found
that the BD processing cost through the proposed technology could be half of that of
the actual conventional methods
Reference is made to the US Patent Application by Gleason, Rodney J., et al.42 for
biodiesel fuel and method of manufacture therefor by Supercritical method.
Typical salient points of the invention are stated below:
Generally, such fuels are prepared by the trans-esterification of a triglyceride(s)
either: (a) in the presence of a catalyst; or (b) by using the alcohol in a supercritical
condition. In a trans-esterification reaction, usually, a fat or oil from any suitable
source, such as corn oil or the like, is reacted with the alcohol to form a fatty acid
ester which can then be successfully deployed as a fuel. This trans-esterification
process is well-known, such as described in U.S. Patent Nos. 6,570,030, 6,187,939, and
6,090,959; as well as U.S. Publication No. 2006/0025620, the disclosures of which are
hereby incorporated by reference. However, the efficiency of such processes is not
satisfactory. In the catalytic reaction, because of the presence of the catalyst and the
potential for soap by-products, the efficiency of such a reaction system is somewhat
degraded. Similarly, in the non-catalytic reaction, because excess stoichiometric
quantities of alcohol are used, the economics of the process lessen the practicality of
using same.
60
A method for producing biofuel by a trans-esterification reaction of an alcohol and a
triglyceride such as an oil or fat is carried out at supercritical conditions in a reactor
using a stoichiometric excess of alcohol.
The reaction products of biofuel and gaseous mixture of glycerin and alcohol are re-
cycled through a series of heat exchangers which transfer heat to respective pre-
heaters to sequentially raise the temperature and pressure of the reaction mixture
prior to delivery to the reactor. Any excess alcohol after separating and recovering
gaseous glycerin there from is recycled and mixed with "fresh" alcohol. Preferably,
the process is a non-catalytic continuous process.
Thus, there exists a need for improvements in the manufacturing process whereby
the excess reactants can be recycled and reused. It is this to which the present
invention is directed.
According to the present invention, and in a preferred embodiment, a stoichiometric
excess of an alcohol is reacted with a vegetable oil in a suitable reactor which is
maintained at supercritical conditions, i.e. at a temperature above about 180o C and a
pressure greater than about 1450 psi. Prior to delivering the reactants to the reactor,
the alcohol is passed through a series of pre-heaters. The pre-heaters use recycled
reaction products to pre-heat the alcohol.
According to the present invention, after leaving the reactor, a portion of the reactor
products are passed into a heat exchanger to transfer heat to a proximal pre-heater
and then on to a first flash drum which condenses the biodiesel fuel while leaving
the excess alcohol and glycerol by-product in a gaseous state. Liquid fuel is collected
from the bottom of the drum and sent into another heat exchanger which transfers
heat to a first intermediate pre-heater. The liquid fuel is then collected, while the
alcohol and glycerol are transferred to an additional heat exchanger which transfers
heat to a second intermediate pre-heater, and then into a second flash drum.
The second flash drum is then set to a temperature and pressure that causes the
glycerol to condense, while leaving the alcohol in a gaseous state. The glycerol is
collected from the second drum and the gaseous alcohol is then recycled, condensed,
and mixed with fresh alcohol which, in turn, is then pumped into the reactor through
the pre-heaters.
Preferably, the reaction is a continuous process, although a batch process could be
employed.
It should be noted that although the catalytic reaction can be used, it is preferred that
the supercritical reaction be employed for efficiency and not having to recover the
catalyst.
61
4.12 BIODIESEL PRODUCTION UNIT43
The patent describes a modified reactor, reactor mixing system, reaction system, a
basic catalyst material, equipment system, pretreatment of the feedstocks and
separation and purification of the products
A useful biodiesel reactor system includes a reactor recirculation line running from
the reactor bottom to a headspace in the top of the reactor. A reactor recirculation
pump is in the reactor recirculation line, and a reactor nozzle is positioned in at a
reactor recirculation line discharge in the headspace. The reactor nozzle provides
back pressure on the reactor recirculation pump to cause a controlled cavitation. The
controlled cavitation provides mixing for the various reactants to produce biodiesel
fuel.
4.13 PROCESS FOR THE CONVERSION OF RENEWABLE OILS TO LIQUID
TRANSPORTATION FUELS44
A method of producing a hydrocarbon product by hydrotreating a feedstock
comprising triacylglyceride (TAG) in the presence of a nonsulfided hydrotreating
catalyst to produce a first product comprising hydrocarbons is described.
According to this disclosure, a feedstock comprising TAG is hydrotreated
(hydrodeoxygenated).
The TAG may be obtained from terrestrial or marine sources. The TAG feedstock
may comprise triacylglycerides derived from plants, triglycerides derived from
animals, triglycerides derived from algae, or combinations thereof. The TAG
feedstock may further comprise diacylglycerides, monoacylglycerides, FFAs, and
combinations thereof as contaminants.
The TAG feedstock may comprise yellow grease, brown grease, or a combination
thereof. The TAG feedstock may comprise a blend of fresh TAG and used TAG (i.e.
yellow grease and/or brown grease).
The ratio of the virgin and used TAG and/or the composition of the TAG feedstock
may be selected such that hydrotreating produces a desired hydrocarbon product
slate.
The term "brown grease" comprises trap grease, sewage grease (e.g., from a sewage
plant), and black grease. Brown grease from traps and sewage plants are typically
unsuitable for use as animal feed.
The term "brown grease" also encompasses other grease having a free fatty acid
(FFA) content greater than 20% and being unsuitable for animal feed.
43. West, J., et al., Biodiesel Production Unit, 2010 , US Patent Application 20100095581 (Annexure 12) 44. Strege, Joshua R. , et al., Process For The Conversion Of Renewable Oils To Liquid Transportation Fuels, 2010, US patent
application 20100113848 (Annexure 13)
62
The term "yellow grease" comprises used frying oils from deep fryers and restaurant
grease traps. It also encompasses lower-quality grades of tallow from rendering
plants.
4.14 IMPROVED AND INNOVATIVE PROCESS FOR THE PREPARATION
OF FATTY ACID METHYL ESTER FROM TRIGLYCERIDE OIL BY
TRANS-ESTERIFICATION USING MECHANICALLY EXPELLED OIL
FROM JATROPHA SEEDS45
The present invention is to provide an improved process for the preparation of fatty
acid methyl ester (biodiesel) from oil expelled mechanically from whole seeds of
Jatropha curcas.
Biodiesel is produced from raw oil under ambient conditions by first removing FFA
and other impurities from the oil and thereafter using a single step KOH-catalysed
trans-esterification followed by a novel work up based on initial washing of crude
fatty acid methyl ester with glycerol followed by washing with water to remove
traces of remaining impurities.
The work up confines all the excess methanol and alkali in glycerol, which is then
processed with greater cost-effectiveness and energy-efficiency to recover individual
constituents (methanol, glycerol, potash) from the mixture.
A further novelty is the use of flue gases in the above process. Biodiesel complying
with EN14214 specification is obtained in >96% yield (w/w) w.r.t. neutralized oil
and all by-products obtained are of commercial value. As a result of the above
inventions, the effluent load is at a minimum.
The present invention provides an improved process for the preparation of fatty acid
methyl ester (biodiesel) of triglyceride oil that comprises:
expelling oil from whole seeds and keeping aside the cake for application as
organic manure,
neutralizing excess free fatty acid in the oil with alkali and separating the soap
cake,
adding an antioxidant and sparging the oil with dry air to reduce moisture
content,
treating the oil with appropriate quantity of methanolic-KOH solution that is
dried with anhydrous sodium sulphate,
separating the glycerol layer formed during the reaction by known technique,
treating the fatty acid methyl ester layer with glycerol in two lots to further
reduce methanol, catalyst and other impurities in the fatty acid methyl ester
layer, separating the glycerol layers by known technique,
washing the fatty acid methyl ester layer thereafter with water in two lots to
minimize impurities to desired level,
separating the aqueous washings by known technique,
45. Ghosh, P.K., et al., Process for the preparation of fatty acid methyl ester from triglyceride oil by transesterification. Patent
US7666234 (Issue date Feb 23, 2010)
63
adding additional quantity of antioxidant to the fatty acid methyl ester and
sparging with dry air to minimize moisture content,
collecting the glycerol layers and treating with SO.sub.x or flue gas to convert
the spent KOH catalyst into K.sub.2SO.sub.4 or K.sub.2CO.sub.3, respectively,
adjusting the pH to desired level and distilling off the methanol in glycerol
layer, hot centrifuging the remaining mass to separate out potassium salt from
glycerol,
washing the salt to remove adhering impurities,
keeping aside required amount of the crude glycerol for washing of the fatty
acid methyl ester layer of subsequent batch and also for other applications
where crude glycerol is directly useful, and
distilling the remaining crude glycerol having low water content to produce
refined, neat glycerol.
4.15 REACTIVE DISTILLATION METHODS AND SYSTEMS FOR ALKYL ESTER
PRODUCTION46
This application relates to alkyl ester production, and especially relates to the
continuous reaction/separation in the production of alkyl ester.
Most of the production of biodiesel fuel is carried out in batch reactors, where
measured quantities of the triglycerides, methanol, and catalyst are added to a tank,
heated, and mixed for a period of time ranging from 1 hour to several hours. After a
period of time, the reacted mixture is pumped to another vessel and allowed to sit,
quiescent for a second period of time. The mixture then phase separates into a
biodiesel layer and a glycerol layer, and the glycerol layer is drained. The resulting
biodiesel is then further purified.
In some currently used processes, continuous centrifuge technology is used to
separate glycerol, and carry out the water washing steps to remove residual alcohol
from the biodiesel product. Also, current patent applications include flash separation
of methanol from the biodiesel as an alternative method to the water-washing step.
Some current processes apply distillation methods to separate the biodiesel from the
glycerol byproduct based on their volatility differences. In one current process,
biodiesel separation from glycerol is claimed to occur in a reactor where the feed is
introduced at the top and an impure biodiesel stream and an impure glycerol stream
are both withdrawn near the bottom.
In prior art process, both desired product biodiesel and byproduct glycerol are
withdrawn near the bottom of the reactor as liquid streams. The proximity of the
withdrawal points for these two product streams implies there will be significant
mixing and cross-contamination. This assertion is born out by the presence of many
downstream separators and complicated processing required to further purify the
products. In this process, the concentration of both products, biodiesel and glycerol,
46.
Parnas, R., et al., Methods and systems for alkyl ester production, 2009, US patent application 20090038209 (Annexure 14)
64
increases towards the bottom of the reactor, thereby hindering the conversion
process.
The processes based on reactive distillation produce high purity glycerol and high
purity biodiesel with small amounts of residual methanol. However, these processes
are energy intensive due to the necessity of providing large quantities of heat to boil
the bottoms product and produce the vapor stream for the distillation column.
Distillation processes separate materials having different volatility by successively
vaporizing higher and higher purity streams of the more volatile material and
successively condensing higher and higher purity streams of the less volatile
material. This process depends on the equilibrium between vapors and liquids, and
is driven by the heat input necessary to boil the material.
The current method constitutes a lower energy consumption process than the
reactive distillation process. The details of the process are discussed in the patented
reference.
4.16 MODIFIED REACTOR, APPARATUS FOR EFFICIENCY
IMPROVEMENTS IN ESTERIFICATION AND TRANS-
ESTERIFICATION47
Esterification and trans-esterification methods, systems and apparatus are disclosed
which increase the efficiency of esterification reactions.
The methods utilizing an annular gap reactor comprises a rotor rotating within a
stator to provide an annular flow passage comprising a flow path containing a high-
shear treatment zone in which the passage spacing is smaller than in the remainder
of the zone to provide a subsidiary higher-shear treatment zone.
In exemplary embodiments, the reactor is modified to include an evaporator portion
including an opening in the stator near the end of the reactor and a series of fins
placed in the opening.
Increase in the rates due to the annular gap reactor allow for the use of less catalyst,
poorer catalysts, lower temperature and reduction in unwanted side reactions at
more economically favorable conditions.
In one aspect of the present disclosure, a method to efficiently conduct esterification
and trans-esterification reactions is disclosed. The method involves providing an
annular gap reactor to provide more efficient mixing, wherein the annular gap
reactor is operating in laminar flow conditions in the absence of Taylor vortices.
Reactants are introduced into the annular gap reactor, and mixed to produce the
desired ester.
In another aspect, the annular gap reactor comprises a rotor rotating within a stator
to provide an annular flow passage comprising a flow path containing a high-shear
47. Lichtenberger, P.L., et al., Esterification and transesterification systems, methods and apparatus, 2010 , US Patent 7,678,340
(Annexure 15)
65
treatment zone in which the passage spacing is smaller than in the remainder of the
zone to provide a subsidiary higher-shear treatment zone.
In another aspect, the annular gap reactor may be modified to provide an evaporator
attached to the annular gap reactor, the evaporator including an opening in the stator
near the end of the reactor and a series of fins placed in the opening.
In a further aspect, a reactor is disclosed that encompasses a closed system
continuous reactor that can increase esterification reaction rates over that of
traditional batch style reactions. In some examples, reactor esterifications were 5-120
times faster than with batch systems.
In another aspect of the disclosure, equipment and reagents can help drive the
reaction past batch equilibrium yields.
In a further aspect, higher shear rates in the reactor lead to higher yields.
Additionally, higher catalyst loadings increase the reaction rate.
In an exemplary embodiment, a trans-esterification reaction of vegetable oil with
methanol to produce methyl esters (biodiesel) was performed in the reactor. The use
of the reactor greatly increases the speed of the main reaction. The increase in
reaction rate due to use of the annular gap reactor is of much greater importance
than either temperature or the type of catalyst used.
In a further aspect, the increase in the reaction rates caused by the reactor allow for
the use of less catalyst, less efficient catalysts, lower temperatures and reduction in
unwanted side reactions at more economically favorable conditions. In particular
embodiments, sodium hydroxide can be utilized, instead of the more expensive
sodium methoxide, as a catalyst in the annular gap reactor disclosed herein
achieving equivalent yields with less residence time.
Having discussed the trans-esterification for biodiesel, the other two methods of
pyrolysis and emulsification are stated in the following sections 4.17 and 4.18.
4.17 PYROLYSIS AND CRACKING FOR BIODISEL PRODUCTION11
Pyrolysis is a method of conversion of one substance into another by mean of heat or
by heat with the aid of the catalyst in the absence of air or oxygen. The process is
simple, wasteless, pollution free and effective compared with other cracking
processes. The reaction of thermal decomposition is shown below.
The mechanism of thermal decomposition of triglycerides
66
.
Because of the possibility of producing triglycerides in a wide variety of products by
high-temperature pyrolysis reactions, many investigators have studied the pyrolysis
of triglycerides to obtain products (liquid, gas, and solid) suitable for fuel under
different reaction conditions with and without catalyst. Pyrolysis results in the
production of alkanes, alkenes, alkadienes, carboxylic acids, aromatics, and small
amounts of gaseous products. Depending on the operating conditions, the pyrolysis
process can be divided into three subclasses: conventional pyrolysis, fast pyrolysis,
and flash pyrolysis. The conversion of oil was high (42–83 wt%) and the product
distribution depended strongly on the reaction temperature, residence times, and
catalyst content. The pyrolysis products consisted of gas and liquid hydrocarbons,
carboxylic acids, CO, CO2, H2, and water.
4.18 MICRO-EMULSIFICATION
Micro-emulsification is the formation of microemulsions (co-solvency) which is a
potential solution for solving the problem of vegetable oil viscosity. Microemulsions
are defined as transparent, thermodynamically stable colloidal dispersions in which
the diameter of the dispersed-phase particles is less than one-fourth the wavelength
of visible light. Microemulsion-based fuels are sometimes also termed ‘‘hybrid
fuels”, although blends of conventional diesel fuel with vegetable oils have also been
called hybrid fuels.
To solve the problem of the high viscosity of vegetable oils, microemulsions with
immiscible liquids, such as methanol, ethanol and ionic or non-ionic amphiphiles
have been studied. It has been demonstrated that short-term performances of both
ionic and non-ionic microemulsions of aqueous ethanol in soybean oil are nearly as
well as that of No. 2 diesel fuel. Ziejewski et al.48 prepared a microemulsion
containing 53% (v/v) alkali-refined and winterized sunflower oil, 13.3% (v/v) 190-
proof ethanol and 33.4% (v/v) 1-butanol. This non-ionic microemulsion had a
viscosity of 6.31 cSt at 313 K, a cetane number of 25, and an ash content of less than
0.01%. Lower viscosities and better spray patterns (more even) were observed with
an increase of 1-butanol.
48.
Ziejewski M et al., Diesel engine evaluation of a nonionic sunflower oil-aqueous ethanol microemulsion. JAOCS 1984;61:1620–6.
67
4.19 SUMMARY
Biodiesel as it is defined today is obtained by trans-esterifying triglycerides with
methanol. Pyrolysis and microemulcification need to be mentioned but of little
importance compared to trans-esterification.
Methanol is the preferred alcohol for obtaining biodiesel because it is the cheapest
alcohol. Base catalysts are more effective than acid catalysts and enzymes.
There are four basic routes to biodiesel production from oils and fats:
Base-catalyzed trans-esterification
Direct acid-catalyzed trans-esterification
Conversion of the oil into its fatty acids and then into biodiesel
Noncatalytic trans-esterification of oils and fats.
Biodiesel produced by trans-esterification reactions can be alkali catalyzed, acid
catalyzed, or enzyme catalyzed, but the first two types have received more attention
because of the short reaction times and low cost compared with the third one.
Most of the biodiesel produced today is made with the base catalyzed reaction for
several reasons:
It involves low temperature and pressure.
It yields high conversion (98%) with minimal side reactions and reaction time.
It allows a direct conversion into biodiesel with no intermediate compounds.
It requires simple construction materials.
Acid catalyst may be used with high FFA in feedstock.
The base-catalyzed production of biodiesel generally occurs using the following
steps:
Mixing of alcohol and catalyst
Trans-esterification reaction
Separation
Biodiesel washing
Alcohol removal
The most important aspects of biodiesel production to ensure trouble-free operation
in diesel engines are:
Complete trans-esterification reaction
Removal of glycerine
Removal of catalyst
Removal of alcohol
Removal of free fatty acids
68
The basic catalyst is typically sodium hydroxide (caustic soda) or potassium
hydroxide (caustic potash). Reaction time varies from 1 to 8 hours, and optimal
reaction time is about 2 hours.
Excess alcohol is normally used to ensure total conversion of the fat or oil into its
esters. After the reaction is complete, two major products form: glycerine and
biodiesel. The glycerine phase is much denser than the biodiesel phase and the two
can be gravity separated with glycerine simply drawn off the bottom of the settling
vessel.
In some cases, a centrifuge is used to separate the two materials faster.
The biodiesel product is sometimes purified by washing gently with warm water to
remove residual catalyst or soaps, dried, and sent to storage.
For an alkali catalyzed trans-esterification, the triglycerides and alcohol must be
substantially anhydrous because water makes the reaction partially change to
saponification, which produces soap. The soap lowers the yield of esters and renders
the separation of ester and glycerol and the water washing difficult.
Low free fatty acid content in triglycerides is required for alkali-catalyzed trans-
esterification. When an alkali catalyst is present, the free fatty acid will react with
alkali catalyst to form soap.
It is common for oils and fats to contain trace amounts of water. When water is
present in the reaction, it generally manifests itself through excessive soap
production. The soaps of saturated fatty acids tend to solidify at ambient
temperatures, so a reaction mixture with excessive soap may gel and form a
semisolid mass that is very difficult to recover.
When water is present, particularly at high temperatures, it can hydrolyze the
triglycerides to diglycerides and form a free fatty acid.
If an oil or fat containing a free fatty acid such as oleic acid is used to produce
biodiesel, the alkali catalyst typically used to encourage the reaction will react with
this acid to form soap. Excessive soap in the products can inhibit later processing of
the biodiesel, including glycerol separation and water washing. Water in the oil or fat
can also be a problem.
Water and alcohol are removed to produce 90% pure glycerine that is ready to be
sold as crude glycerine.
Enzyme catalyst are also useful and known for commercial or semi commercial
applications for biodiesel production. The cost of enzymes, their separation and
circulation are important issues.
Heterogeneous catalytic processes which may be operated in continuous mode have
also been invented. Different types of catalyst have been developed and the process
is helpful in reducing downstream purification.
69
No or very poor miscibility of feed oil with methanol is problematic issue and can be
handled by reacting methanol in supercritical conditions. Supercritical methanol
makes the homogeneous phase of methanol with triglycerides resulting the reactions
to occur fast without the catalyst.
Various designs of contactors, reactors, separations system and catalytic distillations
are used to enhance process efficiency and reduce cost.
The following table shows typical comparisons of different processes.
Table 4.5: Comparative analysis of different biodiesel processes
Variable Alkali catalysis Lipase
catalysis
Supercritical
alcohol Acid catalysis
Reaction temperature (oC) 60-70 30-40 239-385 55-80
Free fatty acid in raw
materials
Saponified products Methyl esters Esters Esters
Water in raw materials Interference with reaction No influence Interference with
reaction
Yield of methyl esters Normal Higher Good Normal
Recovery of glycerol Difficult Easy Difficult Purification of
methyl esters
Purification of methyl
esters
Repeated washing None Repeated
washing
Production cost of
catalyst
Cheap Relatively
expensive
Medium Cheap
Source: J.M. Marchetti et al. / Renewable and Sustainable Energy Reviews 11 (2007) 1300–1311.
Newer developments are taking place to reduce the production costs and use
different kinds of feed stocks.
70
FFuuttuurree DDiirreeccttiioonnss ffoorr PPrroodduuccttiioonn ooff BBiiooddiieesseell
Biodiesel is finding greater applications each day due to various techno-economic factors,
such as rising pollution by fossil fuels, GHG considerations, increasing costs of petroleum,
improvements in manufacturing technologies from various renewable source etc.
Governments, researchers, industrial houses, universities, R & D institutions and NGOs are
considering every possible measure to protect the environment, for which they need to have
competitively available biodiesel production technologies at cheaper costs. In this regard,
some of the important issues are discussed in the section below.
Improvements in the pretreatment of feed, mixing of the raw materials, reactor types,
separation of product, byproducts, recovery of excess alcohol, post treatment for product
purification, operation and operating parameters, better and more active catalysts, catalysts
tolerant to impurities are to be developed further and commercialized.
Cheaper, more abundant and non-competitive feedstocks to edible bio materials are to be
used. Studies on biodiesel synthesis have to be focused on improving and developing such
process technologies with the aim of resolving the various issues outlined above.
5.1 OVERCOMING THE SHORTCOMINGS OF TRANS-ESTERIFICATION
PROCESSES
The majority of commercial biodiesel is made by trans-esterification of vegetable oils
and animal fats with methanol or ethanol in reactors in the presence of base or acids
catalysts. Methanol finds majority of use, and the process is carried out mostly as a
batch operation.
Trans-esterification itself is a reversible reaction and therefore there is an upper limit
to conversion in the absence of product removal.
Alkaline / Acidic trans-esterification has several problems. There are some technical
challenges facing biodiesel production via trans-esterification, which include:
Long residence times, reaction rate can be limited by mass transfer between the
oils and alcohol because they are immiscible
Most commercial processes are run in a batch mode and do not gain some of
the advantages of continuous operation
High operating cost and energy consumption
Low production efficiency
Recovery of glycerol is difficult
Catalyst has to be removed from the product
Alkaline wastewater requires treatment, and free fatty acids (FFAs) and water
interfere with the reaction
Acid catalysts have a slower reaction rate
CCHHAAPPTTEERR 55
71
Impurities or harmful constituents to catalysts have to be taken care of
Alkali catalyzed systems are very sensitive to both water and free fatty acid
content, thus the glycerides and alcohol must be substantially anhydrous
Water makes the reaction partially change to saponification, which produces
soaps, thus consuming the catalyst and reducing the catalytic efficiency, as well
as causing an increase in viscosity, formation of gels, and difficulty in
separations.
It is desirable to have technologies that enhance reaction rate, reduce molar ratio of
alcohol to oil and energy input by intensification of mass transfer and heat transfer
and in situ product separation, thus achieve continuous product in a scalable unit for
successful commercialization.
Some of the required novel reactor systems to be further developed for trans-
esterification are discussed below.
5.1.1 Static Mixers37
Static mixers consist of specially designed motionless geometric elements enclosed
within a pipe or a column and create effective radial mixing of two immiscible
liquids as they flow through the mixer.
Recently, they have been used in continuous biodiesel synthesis in combination with
other equipment
Thompson and He49 used a stand-alone closed-loop static mixer system as a
continuous-flow reactor to produce biodiesel from canola oil with methanol when
sodium hydroxide was used as catalyst.
The experimental setup is shown in Figure 5.1.
49. J.C. Thompson, B.B. He, Biodiesel production using static mixers, Trans. ASABE 50 (2007) 161–165.
72
Figure 5.1: Experimental setup: (a) static mixer closed-loop system, and (b) internal
structure of static mixers
Source: Thompson and He49
The system is composed of two stainless steel static reactors (4.9mmID×300mmlong)
including 34 fixed right and left-hand helical mixing elements. High quality biodiesel
which met the ASTM D6584 specification was obtained after optimization of
experimental conditions.
The most favorable conditions for completeness of reaction included operation at a
temperature of 60oC and using a concentration of 1.5% sodium hydroxide catalyst
and a reaction time of 30min.
The total glyceride content was lower than 0.24 wt% when the molar ratio of
methanol to oil is 6:1.
Boucher et al.50 also reported a reactor/separator design involving a static mixer for
continuous biodiesel production and product separation as shown in Fig. 5.2.
50. M.B. Boucher, et al., Pilot scale two-phase continuous flow biodiesel production via novel laminar flow reactor-separator,
Energy & Fuels 23 (2009) 2750–2756.
73
Figure 5.2: Diagram of laminar flow reactor/separator
Source: Boucher et al.50
Pretreated waste canola oil and the solution of potassium hydroxide in methanol
flow into a static mixer, which was exploited as an injector into a reaction chamber
with no moving parts.
Emulsified reactants were released into the chamber from the mixer with decreasing
bulk velocity and separated into two phases under laminar flow conditions in the
main body of the reactor.
The less dense biodiesel phase separated as an upper layer. The glycerol phase,
which had a higher density, settled as the lower layer.
This required that the bulk flow velocity be set to a value which was lower than the
settling velocity of glycerol.
The new reactor system obtained conversions greater than 99% with simultaneous
removal of 70–99% of the glycerol after 6 hour continuous running.
This was achieved at slightly elevated temperatures (40–50oC), using an overall feed
rate of 1.2 L/min, a 6:1 molar ratio of methanol to vegetable oil triglycerides, and a
1.3 wt% catalyst.
Static mixers present the advantage of low maintenance and operating cost and low
space requirement because they have no moving parts. However, the mixing process
relies mainly on slow, unforced molecular inter-diffusion in the laminar regime and
therefore reactions are still slow.
74
5.1.2 Micro-channel Reactors37
Micro-channel reactors achieve rapid reaction rates by improving the efficiency of
heat and mass transfer and utilizing high surface area/volume ratio and short
diffusion distance.
Canter51 reported that biodiesel could be produced in a microreactor at mild
conditions. Yields of greater than 90% biodiesel after a residence time of 4 min were
reported. Sun et al.52 studied KOH-catalyzed trans-esterification of unrefined
rapeseed oil and cottonseed oil with methanol in capillary micro reactors with inner
diameters of 0.25mm. At a 5.89 min residence time, they obtained a 99.4% yield of
methyl esters at a catalyst concentration of 1wt%KOH and using a 6:1 molar ratio of
methanol to oil and at a temperature of 60◦C.
The configuration of zigzag micro-channel reactors with narrower channel size and
more turns is shown in Fig. 5.3. This type of reactor was shown to intensify the
biodiesel production process by obtaining smaller droplets compared to those micro-
channel reactors with T or Y-flow structures. The microchannel reactor is smaller in
size offering reductions in footprint requirements, construction and operating costs.
Another advantage of micro-channel reactors is ease of scale-up which may be
readily achieved by adding more reactors of the same proven dimensions in parallel.
This approach can reduce the risks associated with scaling up of conventional
reactors.
Figure 5.3: Representative configuration of a zigzag micro-channel reactor
Source: Wen et al.53
5.1.3. Oscillatory flow reactors37
Oscillatory flow reactors are tubular reactors in which orifice plate baffles are equally
spaced and produce oscillatory flow using a piston drive as shown in Figure 5.4.
51. N. Canter, Making biodiesel in a microreactor, Tribol. Lubr. Technol. 62 (2006) 15–17. 52. J. Sun, et al., Synthesis of biodiesel in capillary microreactors, Ind. Eng. Chem. Res. 47 (2008) 1398–1403. 53. Z. Wen, X. Yu, S.-T. Tu, J. Yan, E. Dahlquist, Intensification of biodiesel synthesis using zigzag micro-channel reactors,
Bioresour. Technol. 100 (2009) 3054–3060.
75
Figure 5.4: The configuration of oscillatory flow reactor [9]
Source: Harvey et al.54
When a bulk fluid is introduced into the reactor, an oscillatory motion interacts with
it and intensifies radial mixing, with enhancements in mass and heat transfer whilst
maintaining plug flow.
The reactor can achieve long residence times because the degree of mixing is not
directly dependent upon the Reynolds number of the bulk flow through it, but is
mainly related to the oscillatory conditions.
Hence the oscillatory flow reactor can be designed with a short length-to-diameter
ratio and improves the economy of biodiesel production due to smaller “footprint”,
lower capital and pumping cost, and easier control.
Harvey et al.54 developed a continuous oscillatory flow reactor (OFR) to produce
saleable biodiesel from rapeseed oil in a pilot-scale plant shown in Figure 5.5.
54. A.P. Harvey, M.R. Mackley, T. Seliger, Process intensification of biodiesel production using a continuous oscillatory flow
reactor, J. Chem. Technol. Biotechnol. 78 (2003) 338–341.
76
Figure 5.5: Schematic of oscillatory flow reactor for biodiesel production
Source: Harvey et al.54
The reactor is composed of two vertically positioned jacketed QVF tubes of 1.5m
length and 25mm internal diameter.
Conversions of biodiesel up to 99% were achieved after 30min at 50oC using a molar
ratio of methanol to rapeseed oil of 1.5 and in the presence of a sodium hydroxide
catalyst. Another biodiesel pilot plant using an oscillatory flow reactor was
demonstrated by the Polymer Fluids Group in the University of Cambridge.
One of the advantages of this technology is the very low molar ratio of methanol to
oil they applied. It is lower than the stoichiometric ratio (3:1) required and reduces
significantly the operating cost.
The short length-to-diameter of this reactor decreases capital cost and allows it to be
scaleable.
5.1.4 Cavitational reactors37
Cavitational reactors use acoustic energy or flow energy to generate cavitation
phenomena, which results in process intensification.
Cavitation also intensifies the mass transfer rate by generation of local turbulence
and liquid micro-circulation in the reactor. All of them contribute to the
improvement in processes which under other conditions are limited by mass transfer
and heat transfer.
77
Another reactor design which uses the principle of cavitational mixing is described
by Hydro Dynamics, Inc. Here a Shock- Wave Power Reactor (SPR) based on
“controlled cavitation” is described for process intensification of the trans-
esterification reaction in biodiesel production. A commercial SPR is shown in Figure
5.6.
Figure 5.6: A commercial SPR reactor for biodiesel production developed by
Hydro Dynamics, Inc.
Source: Hydro Dynamics, Inc., http://www.hydrodynamics.com/product pics2.htm
Shock Wave Power Reactor works by taking a feedstock, methanol and catalyst, into
the machine housing, where it is passed through the generator’s spinning cylinder.
The specific geometry of cavities in the cylinder and rotational speed creates pressure
differences within the liquids where tiny bubbles form and collapse. The cavitation is
controlled so that the bubbles collapse only inside the cavities and away from the
metal surfaces and therefore reduce the risk of damaging the material of
construction.
The shock waves increase the surface area of the compounds being mixed so that a
higher mass transfer rate occurs. It takes only several seconds to complete trans-
esterification of vegetable oils or animal fats. Hence, the reactor allows the use of a
variety of feedstocks with a broader range of free fatty acid concentrations because
short reaction time leads to less saponification and emulsification.
5.1.5 Biodiesel Production Unit using cavitation pretreatment and cavitation
reactor43
A biodiesel reactor system includes a reactor recirculation line running from the
reactor bottom to a headspace in the top of the reactor. A reactor recirculation pump
is in the reactor recirculation line, and a reactor nozzle is positioned in at a reactor
recirculation line discharge in the headspace. The reactor nozzle provides back
pressure on the reactor recirculation pump to cause a controlled cavitation. The
controlled cavitation provides mixing for the various reactants, which produces
biodiesel.
Too much cavitation can produce soap, which lowers yields, and not enough
cavitation can increase cycle times and/or decrease yields by not achieving sufficient
mixing.
78
5.1.6 Rotating/spinning tube reactors37
The rotating, or spinning tube reactor is a shear reactor consisting of two tubes. A
scheme of the rotating tube reactor is shown in Figure 5.7.
Figure 5.7: Schematic of a spinning tube reactor
Source: Four Rivers BioEnergy Company, Inc. http://www.rccostello.com/STT.html.
Four Rivers Bio Energy Company, Inc. utilized the technology and developed a
commercial Spinning Tube in a Tube (STT) system for biodiesel production as shown
in Figure 5.8. The STT reactor accelerates the rates of chemical reactions by up to three
orders of magnitude. The trans-esterification reaction of soybean oil and methanol for
biodiesel production is conducted at a residence time of 0.5s. The short residence time
allows this reactor to handle feedstocks with high free fatty acid content. The size of
the reactor is relatively small and it is easy to scale up.
Figure 5.8: Details of the drawing are shown in the referred patent
79
5.1.7 Esterification and trans-esterification systems, methods and apparatus47
Systems and apparatus are disclosed which increase the efficiency of esterification
reactions.
The methods comprising utilizing an annular gap reactor comprises a rotor rotating
within a stator to provide an annular flow passage comprising a flow path
containing a high-shear treatment zone in which the passage spacing is smaller than
in the remainder of the zone to provide a subsidiary higher-shear treatment zone.
In exemplary embodiments, the reactor is modified to include an evaporator portion
including an opening in the stator near the end of the reactor and a series of fins
placed in the opening.
Increase in the rates due to the annular gap reactor allow for the use of less catalyst,
poorer catalysts, lower temperature and reduction in unwanted side reactions at
more economically favorable conditions.
5.1.8 Membrane reactors37
Membrane reactors integrate reaction and membrane-based separation into a single
process. They can increase the conversion of equilibrium-limited reactions by
removing some products from the reactants stream via membranes the study
showed that the membrane reactor could enhance reaction rate by the excellent
mixing in the membrane reactor loop and the continuous removal of product from
the reaction medium.
Figure 5.9: Schematic of biodiesel production in a membrane reactor
Source: Dube et al.55
5.1.9 Centrifugal contactors37
The centrifugal contactor is another process intensification technology. It integrates
reaction and centrifugal separation into a unit. It consists of a mixing zone and a
separating zone as shown in Figure 5.10.
55. M.A. Dube, A.Y. Tremblay, J. Liu, Biodiesel production using a membrane reactor, Bioresour. Technol. 98 (2007) 639–647.
80
As the rotor in the contactor is rapidly rotating within a stationary cylinder, it can
achieve intense mixing and good mass transfer by high shear stress and quick phase
separation by high centrifugal force simultaneously.
However, the residence time in a conventional centrifugal contactor is as low as
about 10 s and cannot allow reaction to reach equilibrium. The researchers at Oak
Ridge National Laboratory56 modified the design of a centrifugal contactor and
achieved the control of residence time in mixing zone. They used the updated
centrifugal contactor to continuously produce biodiesel via base-catalyzed
production.
Figure 5.10 presents the experimental setup for biodiesel production using the
modified centrifugal contactor. At 60◦C more than 99% conversion was achieved
after about 1min using a volumetric phase ratio of 5:1 oil to methoxide and
potassium hydroxide as catalyst when rotor was spinning in 3600 rpm. Good
product separation was realized after 3min. The technology has been
commercialized.
Figure 5.10: Schematic of a centrifugal contactor
Source: McFarlane et al.56
5.1.10 Reactive Distillation
Reactive distillation (RD) is a technique which combines chemical reactions and
product separations in one unit.
Currently reactive distillation has attracted more and more attention and been used
widely due to its many advantages over conventional sequential processes, such as a
fixed-bed-reactor followed by a distillation column. One of the most important
advantages of reactive distillation is that conversion limitation is avoided by
continuous in situ product removal for equilibrium-controlled reactions. Integration
of reaction and separation reduces capital investment and operating costs.
56. J. McFarlane, J.F. Birdwell Jr., C. Tsouris, H.L. Jennings, Process intensification in continuous base-catalyzed biodiesel
production, in: Proceedings of the AIChE Annual Meeting, 2008.
81
For reversible (trans) esterification reaction of vegetable oils with alcohol, usually an
excess amount of alcohol (6:1 or higher alcohol: oil molar ratio) is used to drive the
equilibrium to the product side in order to obtain high conversion rates and high
final equilibrium conversion.
Since recovery of excess alcohol from the esters and glycerol streams involves
additional operating cost, application of reactive distillation to biodiesel production
may lead to a more efficient process. He et al.57 reported a novel reactor system using
RD for biodiesel production from canola oil and methanol using KOH as catalyst.
This process has several advantages over conventional biodiesel production
processes.
Short reaction time and high unit productivity,
No excess alcohol requirement,
Lower capital costs due to the small size of RD and no need for additional
separation units.
RD are energy intensive units and attempts have to be made to cut down energy
costs by heat recovery.
Figure 5.11 shows the FAME production process based on reactive distillation.
Figure 5.11: FAMEs production by esterification with methanol in a reactive
distillation column
Source: Kiss et al.58
57. B.B. He, A.P. Singh, J.C. Thompson, A novel continuous-flow reactor using reactive distillation for biodiesel production,
Trans. ASAE 49 (2006) 107–112. 58. A.A. Kiss, A.C. Dimian, G. Rothenberg, Biodiesel by catalytic reactive distillation powered by metal oxides, Energy &
Fuels 22 (2008) 598–604.
82
5.1.11 Method of Biodiesel Production59
The invention relates to the process of producing biodiesel via trans-esterification
reaction where the feed of vegetable oil and/or animal fat is atomised prior to the
reaction. The process is suitable for continuous production of biodiesel by reacting
the atomised feed with gaseous alcohol in the presence of an effective amount of a
trans-esterification catalyst.
The process is controlled by both a mass transfer and a kinetic stage. By operating at
a higher reaction temperature and using methanol vapor, the kinetic barrier can be
reduced, allowing a shorter reaction time.
Pressure
One of the benefits of the process of the invention is that the principal reaction can be
carried out at atmospheric pressure. This is a distinct advantage simplifying reactor
design.
This process requires less equipment such as mechanical agitators and distillation
columns that are required for batch and some continuous processes operating at
higher pressures.
In practice the actual pressure may be slightly above atmospheric due to the influx of
gaseous methanol and atomised feed reagent into the reactor. The use of atomised
feed material gives rise to increased contact surface area thereby assisting the
reaction by decreasing the mass transfer resistance.
5.1.12 Heterogeneous catalysts, continuous process
Heterogeneous catalysts are promising for the trans-esterification reaction of
vegetable oils to produce biodiesel. Unlike homogeneous catalysts, heterogeneous
catalysts are environmentally benign and can be operated in continuous processes.
Moreover, they can be reused and regenerated The use of catalyst supports such as
alumina, silica and zinc oxide could improve the mass transfer limitation of three
phase reactions.
Furthermore, by anchoring metal oxides inside pores, catalyst supports could
prevent active phases from sintering in the reaction medium. Solid catalysts
eliminate the need for water washing, reducing wastewater from plants. However,
this kind of process normally requires high pressure and temperature. This leads to
the decomposition of glycerol and other negative side effects.
The formation of the secondary liquid phase, whether it is glycerol or water, also
negatively affects the reaction by deactivating the solid catalyst. To avoid the
deactivation of the catalyst by the second liquid phase formed by glycerol or water,
high temperature is employed. The temperature needed for a base-catalyzed process
can be as high as 180 - 210°C.
59. Mohammed et al., Method of Biodiesel Production, 2009, US Patent Application 20090038209
83
As the process operates at higher temperature and pressure, capital costs are higher
than standard design biodiesel plants.
Utility costs are increased.
Catalin have developed solid catalyst overcoming various production problems.
Typical considerations for CATALIN'S Catalysts (Wayen O Turner, Iowa State
University, Bioeconomy Conference Sept 2008) are stated as under:
Are solid (powder) heterogeneous catalysts
Are used in a water free process
Don’t require neutralization and pH control systems
Run in smaller, less capital intensive plants
Are recyclable
React at industry standard temperature and pressures
Can be easily implemented in existing facilities
Can be used with a wide range of low FFA feedstocks
Have been proven in Bench Top and Batch Pilot Plant production
Can reduce operational costs by ≈ $0.20/ gallon
Produce a higher quality Biodiesel and Glycerin
Nevertheless, one of the major problems associated with heterogeneous catalysts is
the formation of three phases with alcohol and oil which leads to diffusion
limitations thus lowering the rate of the reaction.36
One way of overcoming mass transfer problem in heterogeneous catalysts is using
certain amount of co-solvent to promote miscibility of oil and methanol and
accordingly accelerate the reaction rate.
Tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), n-hexane and ethanol were
used more frequently as co-solvent in trans-esterification of vegetable oils with
methanol and solid catalysts.
CaO was used as a solid base catalyst for trans-esterification of rapeseed oil with
methanol and after 170 min of reaction time methyl ester yields of 93% were
obtained.
However, by adding certain amount of THF into rapeseed oil/ methanol mixture the
same yields of 93% were observed after 120 min of reaction time.
Another way to promote mass transfer problems associated with heterogeneous
catalysts is using structure promoters or catalyst supports which can provide more
specific surface area and pores for active species where they can anchor and react
with large triglyceride molecules.
Studies have been carried out to synthesize and develop new solid catalysts for
trans-esterification reaction in order to overcome some of the disadvantages of use of
homogeneous catalyst and more likely to reduce the cost of biodiesel production and
no fast deactivation of catalyst.
84
A new commercial continuous biodiesel production process is discussed. A solid
catalyst consisting of zinc oxide and alumina was used and results showed that the
process does not require any post treatment to remove the catalyst from biodiesel.
Methyl ester yields, close to theoretical value, were achieved at high pressure and
temperature.
Moreover, glycerol obtained through this process had a purity of approximately 98%.
Type of precursors of active materials has significant effect on the catalyst activity of
supported catalysts. However active site concentration was found to be the most
important factor for solid catalyst performance.
The amount of methyl ester yields and conversion of oils depend on not only catalyst
activity but also the type of oils and the applied operation
5.1.13 Development of enzymatic catalysts
Better catalysts and process steps are needed to be developed for overcoming various
problems of trans-esterifications by homogeneous and heterogeneous catalysts.
The use of lipase is a great viable method for production of ester from different
sources of oil or grease. Research on this topic is still in progress due to the enzyme
flexibility and adaptability to new process.
The main advantage of the enzymatic approach is that the reaction can be carried out
in mild conditions. The enzymatic approach can handle both trans-esterification and
esterification simultaneously.
In the past, applications of the enzymatic approach did not make use of an inert
solvent. As such, the reaction time was deemed too long and the biocatalyst was
eventually deactivated by glycerol or water.
Only a batch operation was possible and the overall operating cost was determined
to be high. Even then, product quality is unpredictable as the immobilized lipase
deactivates after several runs.
Enzymatic catalysis’ are very costly but have following benefits:
Enzymatic catalysts like lipases are able to effectively catalyze the trans-
esterification of triglycerides in either aqueous or non-aqueous systems.
Byproduct, glycerol, can be easily recovered with simple separation processes.
Enzymatic catalysts are often more expensive than chemical catalysts, so
recycling and reusing them is often a must for commercial viability.
Research is needed to bring down the cost for such enzymatic catalytic technologies
conditions.
85
5.2 NONCATALYZED TRANS-ESTERIFICATION
There are two non-catalyzed trans-esterification processes.
These are the BIOX process and the supercritical alcohol (methanol) process.
Supercritical process is known to be commercialized. However for further
improvement, R & D is needed for both the processes.
5.2.1 BIOX Process13
It is a continuous process and is not feedstock specific. The BIOX process handles not
only grain-based feedstocks but also waste cooking greases and animal fats.
The unique feature of the BIOX process is that it uses inert reclaimable cosolvents in
a single-pass reaction taking only seconds at ambient temperature and pressure.
The BIOX process uses a cosolvent, tetrahydrofuran, to solubilize the methanol.
Cosolvent options are designed to overcome slow reaction times caused by the
extremely low solubility of the alcohol in the triglyceride phase.
5.2.2 Noncatalytic and Catalytic Supercritical process- One and Two Step
Approaches60
To overcome various drawbacks in the conventional alkali-catalyzed method, two
novel processes have been developed employing non-catalytic supercritical methanol
technologies and need further studies and directions.
The one-step method could produce biodiesel through trans-esterification of oils/fats
in supercritical methanol with simpler process and shorter reaction time. In addition,
a higher yield of FAME was achieved due to simultaneous conversion of FFA
through methyl esterification. The two-step method, on the other hand, realized
more moderate reaction conditions than those of the one-step method, keeping
advantages previously noted.
By this method, furthermore, high-quality biodiesel could be obtained since glycerol
was removed away before methyl esterification step.
These production methods have a tolerance for FFA and water in oil/fat feedstocks,
especially in case of the two-step method. Therefore, various low-grade waste
oils/fats, such as waste oils from household sector and rendering plant, can be used
as raw materials.
ONE STEP PROCESS
A method for producing biodiesel by a trans-esterification reaction of an alcohol and
a triglyceride such as an oil or fat is carried out at supercritical conditions in a reactor
using a stoichiometric excess of alcohol.
60. Saka, S. & Minami, E. A Novel Non-catalytic Biodiesel Production Process by Supercritical Methanol as NEDO “High
Efficiency Bioenergy Conversion Project”. The 2nd Joint International Conference on “Sustainable Energy and
Environment (SEE 2006)”, 21-23 November 2006 Bangkok, Thailand
86
The reaction products of biofuel and gaseous mixture of glycerin and alcohol are re-
cycled through a series of heat exchangers which transfer heat to respective pre-
heaters to sequentially raise the temperature and pressure of the reaction mixture
prior to delivery to the reactor.
Any excess alcohol after separating and recovering gaseous glycerin there from is
recycled and mixed with "fresh" alcohol.
Preferably, the process is a non-catalytic continuous process By carrying out the
reaction in a supercritical state, usually at a temperature greater than 180oC and at a
pressure greater than about 1450 psi, the need for a catalyst is eliminated.
In carrying out the reaction, a stoichiometric excess of alcohol is used to ensure
maximum trans-esterification, i.e. about 95%.
According to the present method, the recovery of and reuse of the stoichiometric
excess of alcohol lowers the amount of "fresh" alcohol necessary to be used in the
reaction, while effectively recovering the biofuel.
Furthermore, the heat transferred to the pre-heaters reduces the amount of heat lost
in the reaction by-products, thereby increasing the energy efficiency of the entire
process.
Figure 5.12: One-step supercritical methanol method (Saka process) for biodiesel
production (Shiro Saka and Eiji Minami)
In addition, glycerol, which is recovered as a by-product, can then be used for
various other compositions in which glycerol or glycerin is a component.
Supercritical trans-esterification method is more tolerant to the presence of water and
FFAs than the conventional alkali-catalyzed technique, and hence more tolerant to
various types of vegetable oils, even for fried and waste oils.
TWO STEP SUPERCRITICAL PROCESS61
Compared with the alkali-catalyzed method, this one-step supercritical methanol
method (Saka process) has superiorities in terms of reaction time and purification
step. In addition, the yield of BDF is high because of simultaneous methyl
esterification of FFA to fatty acid methyl esters (FAME). These findings indicate that
the supercritical methanol would provide a clue as to establishment of the efficient
biodiesel production process.
61. Saka, S. NEDO Biodiesel Production Process by Supercritical Methanol Technologies. The 2nd Joint International
Conference on “Sustainable Energy and Environment (SEE 2006)”, 21-23 November 2006 Bangkok, Thailand
87
Further efforts are to be made to develop an alternative method through the two-step
preparation; hydrolysis of triglycerides in subcritical water and subsequent methyl
esterification of fatty acids (FA) in supercritical methanol (Saka-Dadan process).
The proposed reaction conditions of this method were 270oC/7~20MPa for
hydrolysis and methyl esterification. For such milder conditions, the common
stainless steel can be applicable.
Figure 5.13: Two-step supercritical methanol method (Saka-Dadan process) for biodiesel
production through hydrolysis
Figure 5.14: Two-step supercritical methanol method (Saka-Dadan process) for biodiesel
production through hydrolysis and subsequent methyl esterification
Catalytic Supercritical Process62
Catalytic supercritical methods should be explored for biodiesel production.
Esterification is catalyzed by solid strong acids to manufacture biodiesel.
Chromatographic, columns of chemically active solids to separate mixtures of
chemicals, could be used to make biodiesel.
62. Jerry W. Kram, Minnesota scientists create new biodiesel manufacturing process, Biodiesel Magazine, March 21, 2008.
Available at: http://www.biodieselmagazine.com/articles/2231/minnesota-scientists-create-new-biodiesel-manufacturing-
process/
88
Zirconia based catalysts may be useful along with Ben Yan, Gyberg and McNeff et al
built and tested a column that mixed oil and alcohol with the catalyst under high
heat and pressure until the mix became supercritical, a state where the mixture
contains properties of both a gas and a liquid.
Under the right conditions in the column, the oil and alcohol were converted into
biodiesel in six seconds.
Gyberg said the column allows for continuous production of biodiesel – as opposed
to the current batch method of production.
A column about 4 inches in diameter and two feet long will be able to produce 3
million gallons of biodiesel per year. The process can also convert glycerin into
dimethyl ether, which is more valuable in the current market.
5.3 REACTOR AND PROCESS DESIGN
Improving the reactor designs and other unit components to have highly efficient
continuous processes for reactions and separation of product and bypoducts and
recycling of unconverted reactants. Improvement in the reactor increase rates, allow
use of less catalyst, lower temperature and reduction in unwanted side reactions at
more economically favorable conditions. Some of them for reactor design and
feeding improvements have been discussed in section 5.1.
5.4 PROCESS OPTIMIZATION
Optimization of process parameters for maximizing conversion, yields, separation,
purification of products and improving economics of homogeneous and
heterogeneous processes.
5.5 CONTINUOUS PROCESSES
A continuous trans-esterification process is one choice to lower the production cost.
The foundations of this process are a shorter reaction time and greater production
capacity. Improvements in pretreatment of raw material, product purification,
recovery of high quality glycerol byproduct and recycling of unused alcohol are
other ways to lower production cost.
5.6 DEVELOPMENT OF ONE-POT PROCESS
A one-pot process combining trans-esterification and selective hydrogenation to
produce biodiesel from hemp (Cannabis sativa L.) seed oil which is eliminated as a
potential feedstock by a specification of iodine value (IV; 120 g I2/100 g maximum)
contained in EN 14214 may need improvements. It gives opportunity to extend the
high un-saturate materials for biodiesel production, thus making a wide portfolio of
raw materials available without interfering with the food market.
89
5.7 ADSORBENTS FOR PURIFICATION
Invention of adsorbent materials to purify biodiesel to provide a biodiesel product
with improved stability, acceptable for use as a fuel. Such adsorbents may be
magnesium silicate, magnesium aluminum silicate, calcium silicate, sodium silicates,
activated carbon, silica gel, magnesium phosphate, metal hydroxides, metal oxides,
metal carbonates, metal bicarbonates, sodium sesquicarbonate, metal silicates,
bleaching clays, bleaching earths, bentonite clay, and alumina. Each of the above-
mentioned materials may be employed alone or in combination.
5.8 REACTIVE DISTILLATION
Reactive distillation produce high purity glycerol and high purity biodiesel with
small amounts of residual methanol. However, these processes are energy intensive
due to the necessity of providing large quantities of heat to boil the bottoms product
and produce the vapor stream for the distillation column. Although these processes
successfully produce biodiesel fuel, more efficient, economical processes are
continuously sought.
5.9 BIODIESEL FROM SLUDGE
To develop process for producing biodiesel by first extracting lipids from the
sludges generated during primary and/or biological treatment of municipal,
agricultural, and industrial wastewaters using primary, secondary, and tertiary
treatments followed by the trans-esterification of the extracted lipids using trans-
esterification conversion into alcohol-based esters.
90
SSiimmuullaattiioonn && MMooddeelllliinngg AAccttiivviittiieess ffoorr
BBiiooddiieesseell pprroodduuccttiioonn
Considerably increased interest on biodiesel production and consequently activities
including process design and engineering, related to optimization of the process parameters
to improve the product quality, economics of operation, reduced downtime, faster rate of
production etc. is motivating researchers and the industry to address all aspects of related to
its production.
Years 2009 and 2010 have seen a spurt of interest in this. In this chapter we list a few of the
interesting studies that have been published. The purpose of doing this is to draw the
attention of all individuals associated with the process and the production activities of
biodiesel, and for them to see if this could benefit them in any way.
Also, it may prompt some to consider newer studies of interest in the area. It is expected that
like in the petroleum and chemical production sectors, where modeling and simulation has
attracted considerable interest and had led to several benefits, the same should also happen
for the biodiesel production sector.
6.1 SIMULATION OF THE REACTIVE DISTILLATION PROCESS FOR
BIODIESEL PRODUCTION
The trans-esterification reactions in biodiesel production require an alcohol excess for the
reaction to be carried out completely. This excess alcohol should be recovered in order to
purify biodiesel and re-cycle it to the trans-esterification reactor. This results in an
additional demand of energy and operating costs. Reactive distillation is the
simultaneous implementation of reaction and separation within a single unit operation.
This combined operation is particularly suited for liquid phase liquid reactions that
must be carried out with a large excess of one reactant. In this study, the Surface
Response methodology and the Aspen Plus software were used for simulating
biodiesel production by reactive distillation, with the aim of obtaining a deep
understanding of the process and finding the best conditions for producing the
largest amount of fatty acid esters and assess its stability.
CCHHAAPPTTEERR 66
91
Figure 6.1: Flowsheet of the biodiesel production process by reactive distilation63
After various assays, it was concluded that a high yield percentage in the trans-
reaction can be achieved using an oil flow rate of 20.5 grams/minute, and ethanol: oil
ratio of 13, a Molar Reflux rate of 3.51 and a distillate: feed ethanol ratio of 0.84. It
was seen that the reaction time could be diminished, since the simulations were
made for a 1 minute residence time at the pre-reactor, compared to a reaction time of
30 minutes in the conventional process.
6.2 EXCESS METHANOL RECOVERY IN BIODIESEL PRODUCTION
PROCESS USING A DISTILLATION COLUMN: A SIMULATION STUDY
The study uses Aspen Plus Simulation for excess methanol recovery in continuous
biodiesel production process, using a distillation column. The feedstock considered
was tri-oliene, containing 50% Free Fatty Acid (Oleic Acid). Special attention was
devoted to the effect of different alcohol to oil ratio, and important design and
operating parameters of distillation column on excess methanol recovery. The energy
consumption was represented by Re-Boiler heat duty of distillation column.
Figure 6.2: Biodiesel Production Process with possible Methanol Recovery Units
The simulation study shows that for a given distillation operating condition and
parameters, it is possible to recover 95 – 98 % of excess methanol before phase
separation of biodiesel and glycerol.
63. Santander et al, Simulation of the reactive distillation process for biodiesel production . 20th European Symposium on
Computer Aided Process Engineering, Editors: Si. Pierucci and G. Buzzi Ferraris, Elsevier B.V. 2010
92
Table 6.1: Simulation basis
Feedstock Triokin (Triglyceride) with 15% Oleic Acid (FFA)
Biodiesel production process Acid catalysis followed by alkali catalysis (Two
Steps Process)
Methanol to oil ratio 6:1 to 50:1
Methanol recovery unit Distillation column
Reactor subroutine RStoic
Distillation subroutine RadFrac
Reactor Operating Temperature 65oC
Reactor operating pressure 1 atm
Feed temperature in reactor (Methanol & Oil) 25oC
Feed Pressure in Reactor 1 atm
Thermodynamic model UNIFAC
Yield Esterification (100% conversion of FFA)
Transertarification (97% conversion Triglyceride)
Total Biodiesel Production capacity 7,500 tonnes of biodiesel per year
Table 6.2: MRU design specification
Feed temperature 80oC
Feed pressure 0.5 to 1
Total number of stages 10
Feed stage 5
Reflux ratio 1 to 4
The study concludes that alcohol to oil ratio used in the biodiesel production is the
most important process parameter for the development of the methanol recovery
unit, as the energy requirement increases with the increase in methanol to oil ration
used.
Figure 6.3: Process Flow sheet Developed in ASPEN PLUS64
64. Dhar, B.R. & Kirtania, K. Excess methanol recovery in biodiesel production process using a distillation column: A
simulation study. Chemical Engineering Research Bulletin, 13 (2009)
93
Also, it is possible to get higher purity of methanol for a reflux ratio of 1, as the
boiling point of methanol is low as compared to biodiesel and glycerol.
The study also showed that the required re-boiler heat duty can be reduced under
vacuum operation of the distillation column.
6.3 PROCESS OPTIMIZATION FOR BIODIESEL PRODUCTION FROM
CORN OIL AND ITS OXIDATIVE STABILITY
In this research article, Response Surface Methodology (RSM), based on Central
Composite Design (CCD) was used to optimize biodiesel production process from
corn oil. The process variables, temperature and catalyst concentration were found to
have significant influence on biodiesel yield. The optimum combination derived for
high corn oil methyl ester yield (99.48%) was found to be 1.18% wt. catalyst
concentration at a reaction temperature of 55.6oC.
Storage time and Oxygen availability were considered as possible factors influencing
oxidative instability. Results showed that the Acid Value (A.V.) Peroxide Value (P.V.)
and Viscosity (v) increased while the Iodine Value (I.V.) decreased when the
biodiesel was stored for a period of 30 months. These parameters changed very
significantly when the sample was stored under normal oxygen atmosphere.
However, the v, A.V. and I.V of the sample, which was stored under Argon
atmosphere, were within the limits of EN 14214.
Figure 6.4: Experimental yield versus temperature and catalyst concentration
Temperature (XT), catalyst concentration (XC), and catalyst concentration-
temperature interaction effects (XTC) were fitted by multiple regression analysis to a
linear model. The response function for the significant main effects and interactions
is.
94
The statistical analysis of experimental results revealed that the most significant
factor is the catalyst concentration, while it also shows a significant value for
curvature for the chosen responses. These data indicate the nonlinearity of the model
and thus justifies planning a more complex design to fit the data to a second-order
model.
Nonlinear Stage. To better predict the effect of variables, a quadratic model was
investigated. Here, the 22 experiment design was expanded to a circumscribed
central composite design by the addition of 4 new experiments (run 9–12 in Table 2),
called start points and coded •}α. The value of α, which is the distance from the
center point to the start point, is 2n/4, where n is the number of factors (for two
factors, α = 1.414).
The corresponding model is the complete quadratic surface between response and
the factors, given by the equation
where Y is the response (methyl ester yield), Xi and Xj are the uncoded independent
variables, and β0, βi, βii, and βi j are intercept, linear, quadratic and interaction
constant coefficients, respectively. The coefficients of (2) were determined by
multiple regression analysis. This analysis includes all the independent variables and
their interactions, regardless of their significance levels. The best-fitting response
surfaces found can be written as follows:
Source: N. El Boulifi et al., Complutense University, Spain 2010
The statistical model was obtained from coded levels. Equation (3) can be
represented as dimensional surfaces and contour plots, as shown in Figure 6.4. These
show the ester yield predicted for the experimental range of temperature and initial
catalyst concentration. The influence of these variables on the ester yield will now be
discussed. The influence of the main factors and interactions will be derived from (1)
and (3).
Influence of Temperature: For both linear and nonlinear models, the temperature
influence is statistically significant in the range studied. This effect has a positive
influence on the response. As the temperature increases, the solubility of methanol in
the oil increases and so does the speed of reaction. As a matter of fact, at low
temperatures, methanol is not soluble at all in the oil; when the stirring is started an
emulsion appears. The reaction takes place at the interface of the droplets of alcohol
95
in the oil and then as soon as the first FAMEs are formed, the alcohol solubilizes
progressively because the esters are mutual solvents for the alcohol and the oil.
6.4 ECONOMIC ISSUES RELATED TO CONTINUOUS SUPERCRITICAL
BIODIESEL PRODUCTION65
This study focuses on the cost-effectiveness and price risk effects of the supercritical
methanol biodiesel production technology, where by using supercritical conditions
(temperature = 2400C) and pressure =1140psia, Kusdiana & Saka 200416 have shown
that the feedstock and methanol form a single phase that allows more significant
mixing and hence no catalyst is required to speed up the reaction. Here the presence
of water in the feedstock-methanol mixture does not impede the reaction.
To model such a system that is capable of handling feedstock with varying FFA
content, Roberts and Broude ran Pro II chemical process design software to develop
design specification or equipment for a 20 million gallon per year biodiesel facility
using this process. The output for the analysis allows determination of energy
requirements for the system.
Capital investment varies if the design is optimized for feedstock with different
product stream rates. Glycerol production, labour and energy requirement, as well as
waste water flows were monitored across the two different designs. Two data points
for Yellow and Brown grease at expected FFA contents of 15% and 50% were then
used to extrapolate to other FFA content feedstock with reasonable accuracy.
The model’s results suggest, from a processing cost perspective, that FFA content
does not alter non-feedstock cost of production significantly. The study concludes
that this is a significant advantage over traditional alkali-catalyzed trans-
esterification that a biodiesel producer has the ability to source fats and oils with a
wide range of FFA characteristics without suffering significant losses due to soap
formation.
6.5 PROCESS ANALYSIS AND OPTIMIZATION OF BIODIESEL
PRODUCTION FROM VEGETABLE OILS66
The goal of this work was to design and optimize biodiesel production from
vegetable oil. A base case flowsheet was developed for the process. The performance
of the flowsheet along with key design and operating criteria were identified by
conducting computer aided simulation using Aspen Plus.
Various scenarios were simulated to provide sufficient understanding and insights.
Also, different thermodynamic databases were used for different sections of the
process to account for the various characteristics of the streams throughout the
process.
65. Popp, M., et al., Economic Issues Related to Continuous Supercritical Biodiesel Production. Available at:
http://ww2.mackblackwell.org/web/research/ALL_RESEARCH_PROJECTS/3000s/3009/MBTC%20DOT%203009.pdf 66. Lay L. Myint, Process Analysis and Optimization of Biodiesel Production from Vegetable Oils. M.S. Thesis, Texas A&M
University 2007
96
Figure 6.5: Proposed Approach to Synthesizing Separation Network
In order to compare the results, four different separation process scenarios are
simulated:
Removal of methanol first: water washing in the presence of glycerol
Removal of methanol first: water washing after removal of glycerol
Biodiesel and glycerol separation first: water washing in the presence of
methanol
Biodiesel and glycerol separation first: water washing after removal of
methanol
Mass and Energy integration studies were performed to reduce the consumption of
material and energy utilities, improve environmental impact and hence profitability.
At the end, capital cost estimation was carried out using the ICARUS Process
Evaluator computer aided tools, linked to the results of the Aspen Simulation.
97
6.6 STOCHASTIC MODELLING OF BIODIESEL PRODUCTION PROCESS67
The study has described a process for evaluating the uncertainties in the biodiesel
production process arising out of feedstock and operating conditions.
6.6.1 Problem Statement and Approach
The overall objective of this study is to evaluate the impact of uncertainties on the
production of biodiesel by evaluating the amount of biodiesel produced (methyl
ester plus free fatty acid) and the quality of biodiesel produced (methyl ester
content). This evaluation allows a determination of the plant efficiency which could
impact process economics.
The uncertainties which are considered in this study were:
Uncertainties in the feedstock
amount of methanol produced
reactor operating temperature
The approach taken is as follows:
Prepare ASPEN model of biodiesel production process
Specify a fixed mass input to the reactor
Vary the composition of the feed by varying the amount of triglyceride feed to
the reactor
Vary the methanol flow and operating temperatures
To achieve the above, following procedure adopted was:
Use of stochastic simulation block in ASPEN
Uncertainties in feed composition are assigned a probabilistic distribution
function
Graphical analysis of the output results
6.6.2 Stochastic Modeling
Stochastic modeling approach involves the following procedure:
Specifying uncertainty in key parameters
Specifying the correlation structure of any independent parameters
Sampling the distribution of the specified parameters in an iterative fashion
Propagating the effect of uncertainties through the process flow
Applying graphical and statistical techniques to analyze the results.
The benefits of this technique are:
Uncertain parameters can be described
67. Sheraz Abbasi & Urmila Dwivekar, Stochastic Modeling of Biodiesel Production process. University of Illinois, Chicago;
AICHE Annual Meeting, November 2010
98
Impact of uncertainties can be evaluated by describing an output variable and
drawing the cumulative probability distribution (CFD) graphs
The uncertainties propagate though the flow sheet and their impact on plant
efficiency is significant. The evaluation of uncertainties by using Stochastic
Modelling can be extended to other process pathways for determining plant
economics. The results of such a study could be used for plant design, R&D and
selection of feedstock and determining operating envelopes.
99
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Global biodiesel production has witnessed a strong growth trajectory over the last two
decades. From being a subject of scholarly experiments in the late 80’s and early 90’s,
biodiesel is now increasingly looked upon as a viable alternative/addition to the world’s
transportation fuel market, apart from being constantly under research for applications in
other fields as well.
Figure 7.1: Rise in World Biodiesel Production, 1991 – 2005
Source: Research Institute for Sustainable Energy, Murdoch University, Australia
Extensive scientific analyses indicate that given the correct policy and infrastructural fillip,
certain forms of the fuel, such as algal biodiesel and re-processed cellulosic waste, could
bring forth a significant reduction in global crude oil consumption. The added advantages of
reduced emissions and the ever increasing prices of petro-crude have prompted
governments in many nations to come out in support of the technology.
This report deals with the major biodiesel production units active in each region, along with
their production capacities and the kinds of feedstock used.
CCHHAAPPTTEERR 77
100
7.1 REGION 1: ASIA
7.1.1 India
Given its largely tropical/semi-tropical climate, Asia stands to be one of the
powerhouses of biodiesel production. However, its potential has not yet been
matched by output.
For example, India holds significant potential in biodiesel output as it has the climate
and the requisite wasteland available for cultivation of plants like Jatropha Curcas and
Pongamia Pinnata. But the story on the ground is quite the opposite. Indian biodiesel
output has declined since 200868.
Among the reasons quoted for the decline are:
Rising prices of oilseeds due to lack of government intervention in notifying
competitive price points
A sharp arrest in the purchase of oilseeds by Oil Manufacturers on account of
lack of mandates by the Government of India (GOI)
Production in the country has therefore shrunk considerably. Many producers have
halted production, while some have moved on to other avenues entirely.
Future Roadmap
The GOI did however recently come out with the National Biofuel Policy in April
200969. It sets an ambitious roadmap for the country’s biodiesel sector in terms of
plantation and retail mechanisms to be affected to make biodiesel competitive with
petro-diesel. So it remains to be seen how the situation unfolds in the years to come.
Table 1 highlights the major players in the Indian Biodiesel arena.
Table 7.1: Major Biodiesel Producers in India
Major Producers Plant Location Installed Production
Capacity (tons/year) Feedstock Used
Southern Online
Biotechnologies
Choutuppal, Andhra
Pradesh
9,000
All vegetable seed oils [Non
edible], Fish oil, Animal fats,
Fatty acids, Used cooking oil
Naturol Bioenergy
Limited
Kakinada, Andhra
Pradesh
100,000 Palm Oil, Vegetable Oil [Non
edible]
Nova Bio Fuels Panipat, Haryana 9,000 Vegetable Oil [Non edible]
Cleancities Biodiesel
Limited
Visakhapatnam,
Andhra Pradesh
250,000 Jatropha Oil
68.
East or west, home is the best, Nidhi Nath Srinivas, The Economic Times, http://blogs.economictimes.indiatimes.com/something-fresh/entry/east-or-west-home-is
69. National Policy on Biofuels, Ministry of New and Renewable Energy(MNRE), www.mnre.gov.in/policy/biofuel-
policy.pdf
101
Major Producers Plant Location Installed Production
Capacity (tons/year) Feedstock Used
Universal Biofuels Kakinada, Andhra
Pradesh
150,000 Palm Oil, Vegetable Oil [Non
edible]
Emami Group
Haldia, West Bengal
100,000 Jatropha Oil
Source: India Infrastructure Research, Biofuels in India - 2009
7.1.2 China
The Chinese biodiesel industry is still at a nascent stage of development. In contrast
to its booming bio-ethanol exports, China’s biodiesel production stood at roughly
30,000 tons for 2006-0770.
The country’s entire biodiesel sector is under the purview of the National
Development and Reform Commission (NDRC), which has firmly stated that China
will not step into food grain based biodiesel production71.
The intent is admirable, but it severely limits options for producers. China is a net
importer of vegetable oils like soyabean and palm oil. And it currently does not have
in place the volumes of feedstock (such as Jatropha/Pongamia seeds) needed to keep
its biodiesel plants running throughout the year71.
So the only feedstock presently in use is used animal and cooking oil, though these
too are patchy in availability and nowhere near the volumes required for sustainable
production. At the end of 2008, China’s total biodiesel output is estimated to be a
mere 250,000 MT71.
Future Roadmap
However, recognizing the pressing need to substitute the country’s dependence on
fossil fuels, the Government has come out strongly in favor of biodiesel. Since
January 2009,
the NDRC has identified marginal land for exclusive feedstock plantation. Land
in the following provinces has been assessed to be suitable for the purpose:
Yunnan, Sichuan, Hunan, Anhui, Hebei, Inner Mongolia and Shaanxi
the State Forestry Administration (SFA) outlined in 2008 three steps to be
undertaken prior to full scale commercialization of biodiesel:
Variety breeding programs on energy trees – 14 demonstration projects to
be completed by 2010
70.
China: Biofuel industry faces feedstock uncertainty, Joshua Speckman, http://www.environmental-finance.com/download.php?files/pdf/4b7d18404f63a/Bioenergy_report_contents%20.pdf
71. China Biofuels Annual Report 2009, Global Agricultural Information Network,
http://gain.fas.usda.gov/Recent%20GAIN%20Publications/BIOFUELS%20ANNUAL_Beijing_China%20-%20Peoples%20Republic%20of_2009-7-17.doc.pdf
102
22 cultivation demonstration projects to be completed by 2010 to study the
cultivation and harvesting of energy forestry
3 demonstration projects on biodiesel – the following projects have been
sanctioned:
Table 7.2: List of the 3 demonstration projects on biodiesel in China
Three Biodiesel Demonstration Projects approved by NDRC in 2008
Participants Production
Capacity (MT) Location Feedstock
Petro China Province 60,000 Sichuan Jatropha
SinoPec 50,000 Guizhou Province Jatropha
CNOOC 60,000 Hainan Province Jatropha
Source: China Biofuels Annual Report 2009, Global Agricultural Information Network
As per NDRC in 2008, “the construction of the three demonstration biodiesel projects
will help support and regulate the biodiesel sector’s development and avoid
duplicated construction and investment. Three state-own petroleum companies were
selected for the construction of these three projects.
These projects will therefore enable NDRC to glean valuable information on
production and management strategies on the production, storage, marketing and
usage of biodiesel within the country. Jatropha also fits in well with China’s strategy
of re-greening its bare mountains soils (by helping bind the exposed soil and due to
its virtue of low water requirements).
MOU between the United States Department of Agriculture (USDA), Department
of Energy (DOE) and NDRC on scientific, technical an policy aspects of biofuels
development, with focus on technologies such as algal biodiesel
China’s biodiesel sector is therefore moving ahead at a cautious note. Once the
Jatropha plantations bear fruit (by 2011-2012) and the various strategy studies are
concluded, the country’s output is expected to grow to respectable levels by 2020.
A brief of China’s major biodiesel producers is shared under Table 7.3.
Table 7.3: Major Biodiesel Producers in China
Major Producers Location
(Province)
Production
Capacity
(tons/year)
Feedstock Used
Zhonghe Energy Hunan 500,000 n.a.
Gansu Huacheng Biofuel Gansu 200,000 Waste oil
Gushan Environmental Beijing 100,000 Waste oil
China Clean Energy Fujian 100,000 Waste oil
103
Major Producers Location
(Province)
Production
Capacity
(tons/year)
Feedstock Used
Huawu Group Shandong 100,000 Waste cottonseed oil
Xinghuo Bioengineering
Company
Henan 50,000 Waste oil
Gushan Oil Company
& Fat Chemical
Hebei 30,000 Grease waste
Xinyang Hongchang Group Henan 30,000 Local wood plant oil,
grease waste
Gushan Oil Company
& Fat Chemical
Sichuan 12,000 Grease waste, Rapeseed oil
Zhenghe Bio-energy Ltd. Hebei 10,000 Acidified oil, fatty acid
distillates, Pistacia chinensis
Bunge fruit
Source: National Development and Reform Commission (NDRC), China, Malaysian Palm Oil
Council
7.1.3 Malaysia
Malaysia as a biodiesel producer represents a different end of the spectrum
altogether. Its biodiesel output is geared extensively for export to the EU and the US.
The country’s domestic biodiesel consumption is low and it has attracted several
foreign investors in setting up the lucrative palm-based biodiesel production
business72.
However, all is not well with the country’s biodiesel sector. There have been
discordant voices that call for a halt on its dependence on palm oil.
Environmentalists worldwide have raised alarm bells at the rapid clearing of
Malaysia’s forest lands to make way for cultivation of palm trees, as the ecological
disaster such a practice entails would be catastrophic73.
Despite having an installed national capacity of over 10 million tons of
biodiesel/annum, both domestic consumption and international trade has suffered
as the producers are expressing concerns over the lack of domestic subsidy for
biodiesel production. The current situation it seems has made biodiesel significantly
uncompetitive as a commodity. The producers are apparently shifting to more viable
alternatives, like the extraction of palm oil phytonutrients and oleochemical products
to stay afloat74.
72. Malaysia Biofuels Annual Report 2009, Global Agricultural Information Network,
http://gain.fas.usda.gov/Recent%20GAIN%20Publications/Biofuels%20Annual_Kuala%20Lumpur_Malaysia_7-16-
2010.pdf 73. Nestle caves to activist pressure on palm oil, Mongabay.com, http://news.mongabay.com/2010/0517-hance_nestle.html 74. Malaysia's Biodiesel industry at a standstill, Asia News Network, http://www.asianewsnet.net/home/news.php?id=14108
104
Future Roadmap
As voiced by the producers, the Malaysian government will need to step in with
determined directives to help revive the sector, and urgently initiate measures such
as the Mandatory B5 Biodiesel Programme, which currently has been delayed to June
next year.
Table 7.4 highlights Malaysia’s major producers of biodiesel
Table 7.4: Biodiesel Producers in Malaysia
Major Producers Location
Carotino Sdn.Bhd. Pasir Gudang, Johor
Malaysiavegetable Oil Refinery Sdn. Bhd. Pasir Gudang, Johor
PGEO Bioproducts Sdn. Bhd. Pasir Gudang, Johor
Vance Bioenergy Sdn. Bhd. Pasir Gudang, Johor
Mission Biotechnologies Sdn. Bhd. Petaling Jaya, Selangor
Carotech Bio-Fuel Sdn. Bhd. Ipoh, Perak
Lereno Sdn. Bhd. Setiawan, Perak
Golden Hope Biodiesel Sdn. Bhd.-Carey Island Pulau Carey, Selangor
Golden Hope Biodiesel Sdn. Bhd.-Panglima Garang Teluk Panglima Garang, Selangor
Zoop Sdn. Bhd. Shah Alam, Selangor
Global Bio-Diesel Sdn. Bhd. Lahad Datu, Sabah
SPC Bio-diesel Sdn. Bhd. Lahad Datu, Sabah
Source: Directory of Malaysian Palm Oil Industry – Biodiesel
7.1.4 Indonesia
Indonesia holds (possibly) the largest potential on biodiesel production, given its
favorable climatic conditions. But like several other Asian countries, Indonesia’s
biodiesel output has witnessed a sharp decline in recent months.
From nearly 100 million tons in 2007, the country’s biodiesel output fell sharply to
around 70 million tons in 2009 and the downward trend has continued into 2010.
Industry sources say that owing to myriad factors, the country’s biodiesel sector has
suffered a loss of nearly $ 2 billion in the first half of 200975. Nevertheless, the country
is slowly on a rebound and is expected to come through as a major production hub
within the next decade.
75. Indonesia Biofuels Annual Report 2009, Global Agricultural Information Network,
http://gain.fas.usda.gov/Recent%20GAIN%20Publications/General%20Report_Jakarta_Indonesia_6-1-2009.pdf
105
Table 7.5: Biodiesel Producers in Indonesia
Major Producers Installed Capacity
(Tons/annum)
Actual production
(Tons/annum)
Operational Plants
Eterindo Wahanatama Group 120,000 120,000
Platinum Resins Ind. 50,000 50,000
Indo Biofuels Energy 120,000 20,000
Wilmar Bioenergi 700,000 350,000
Sumi Asih Group 200,000 100,000
Planned Plant Capacity
Sinarmas Group 100,000 NA
Darmex Oil 200,000 NA
El Nusa Indobio Energy 200,000 NA
Asian Agro 150,000 NA
Mopoli 150,000 NA
Sampurna/PTPN XI 160,000 NA
Source: Indonesia Biofuels Annual 2009, Global Agricultural Information Network
7.2 REGION 2: AUSTRALIA
Australia falls under the Asia Pacific region. The country has so far posted modest
growth in biodiesel output. It produced a total of 136 million liters in 2008, while
expanding it to 283 million liters in 2009. The government ensures that biodiesel
enjoys an excise-free status as compared to conventional diesel, which is taxed at
AU$0.38143 per liter76.
Future Roadmap
However, large scale future expansion looks circumspect. The country recently faced
its worst drought in a hundred years. The severely strained supplies of fresh water
and the consequent loss of feedstock could hamper Australia’s total biodiesel
volumes. Four additional plants had been under consideration, but given the current
feedstock supply – mainly tallow and waste vegetable oil, only one new plant may
be erected.
Table 7.6 highlights the major Australian biodiesel producers.
76. Australia Biofuels Annual Report 2010, Global Agricultural Information Network,
http://gain.fas.usda.gov/Recent%20GAIN%20Publications/Biofuels%20Annual_Canberra_Australia_07-06-2010.pdf
106
Table 7.6: Major Biodiesel Producers in Australia
Major Producers Location
Annual Production
Capacity (Million liters
/ year)
Feedstock Used
Currently in production
Biodiesel Industries Australia Maitland, NSW 15 Used cooking oil, vegetable
oil
Biodiesel Producers Limited Wodonga, Victoria 60 Tallow, used cooking oil
Smorgon Fuels
Melbourne, Victoria 100 Dryland juncea (oilseed
crop), tallow, used cooking
oil, vegetable oil
Various small producers 5 Used cooking oil, tallow,
industrial waste, oilseed
Total Biodiesel in Production 180
Limited Production
Australian Renewable Fuels Port Adelaide, South
Australia
45 Tallow
Australian Renewable Fuels Picton, Western
Australia
45 Tallow
Total Biodiesel Limited production 90
Biodiesel Plants not in Production
Eco-Tech Biodiesel Narangba,
Queensland
30
Tallow, used cooking oil
Source: Australia Biofuels Annual 2010, Global Agricultural Information Network
7.3 REGION 3: SOUTH AMERICA
Commensurate with Asia, South America also holds immense potential in
harnessing the power of biodiesel. Its climatology is favorable for sustainable oilseed
plantations. Moreover, the continent commands roughly 40% of the land area that
Asia does, while housing only 9% of its population (comparative)77.
This lends it a significant advantage in terms of availability of productive land that
could be diverted towards the biodiesel industry.
7.3.1 Brazil
Being one of the leading countries of the world in renewable energy consumption, Brazil
has had a robust bio-ethanol program operational for decades, successes from which
have enabled the country to make strong inroads into biodiesel production as well.
Brazil’s biodiesel program, called the National Biodiesel production program
(PNPB)78, started in 2004 to affect inclusion of poor farmers from the
77. South America, Wikipedia, http://en.wikipedia.org/wiki/South_America 78.
Brazil Biofuels Annual Report 2010, Global Agricultural Information Network, http://gain.fas.usda.gov/Recent%20GAIN%20Publications/Biofuels%20Annual_Sao%20Paulo%20ATO_Brazil_8-11-2010.pdf
107
underdeveloped regions of the country, especially the North and the Northeast. The
PNPB runs on a unique model of social auctions where the government regulates the
amount of biodiesel to be produced and purchased. Called the ‘Social Fuel Stamp’,
the program mandates producers to:
Purchase minimum raw material percentages from family farmers
Guarantee the purchase of available quantities
Set contracts with farmers, provide technical assistance and training
The system has brought rich dividends. Currently, Brazil has 63 established biodiesel
producers while 19 new ones have authorized74. Production has witnessed a healthy
spurt, as is indicated by Table 7.7:
Table 7.7: Biodiesel Production Growth: Brazil
Year 2006 2007 2008 2009 2010 2011
Biodiesel Production
(in 000 liters)
736 69,002 404,329 1,16,128 2,45,000
(projected)
2,65,000
(projected)
Source: Brazil Biofuels Annual 2010, Global Agricultural Information Network
The success of the Program has also bolstered Brazil’s biodiesel exports. While not yet in
the league of its counterparts, such as Argentina, Indonesia and the US itself, the
country’s exports have witnessed steady increments. An indicative summary of
Brazilian biodiesel exports is as under:
Table 7.8: Brazilian Biodiesel Exports by Country of Destination
(Metric tons, US$ 000 FOB)
Country CY 2008 CY 2009 CY 2010
Quantity Value Quantity Value Quantity Value
Argentina 224 676 1,525 3,559 2,524 4,704
Singapore 99 304 81 154 197 445
China 169 282 202 388 184 424
Uruguay 34 187 37 164 103 286
Chile 119 420 156 648 95 429
Peru 54 227 84 402 51 262
Indonesia 98 148 64 83 48 62
Mexico 21 53 58 118 35 50
Paraguay 142 873 8 42 30 147
Colombia 4 10 62 326 24 121
Others 326 797 154 322 74 259
Total 1,289 3,976 2,432 6,206 3,366 7,187
Source: Brazil Biofuels Annual 2010, Global Agricultural Information Network
Feedstock
While most biodiesel producers have been raging debates over land utilization for
Jatropha plantations, Brazil seems to have stayed clear of the controversy and
focused on other sources. Possibly due to unavailability of wasteland, Brazil’s
108
primary feedstock for biodiesel production has been Soybean oil, followed by animal
fats.
Table 7.9 and 7.10 present an overview of the feedstock used for biodiesel output in
Brazil, and its soybean and cottonseed outputs, respectively.
Table 7.9: Feedstock used in Brazil for biodiesel
Feedstock for Biodiesel Production – Brazil
Soybean 80%
Animal Tallow 15%
Cottonseed Oil 4%
Others 1%
Total 100%
Source: Brazil Biofuels Annual 2010, Global Agricultural Information Network
Figure 7.2: Biodiesel Feedstock options by Region - Brazil
Source: Petrobras, Biodiesel 2020: A Global Market Survey
Future Roadmap
In 2008, a two percent blend in biodiesel (B2) was made mandatory for all mineral
diesels. In January 2010, this rose to a five percent blend (B5), indicating the country’s
strengthening biodiesel output. As of today, there are no indications to suggest an
upward revision in the blending ratio.
However, significant scientific research is being carried out across Brazil (in both bio-
ethanol and biodiesel) to study higher yielding alternatives to oilseeds and plant
cellulose. For example, the National Institute for Science and Technology is reported to
have invested US$1 million for the development of enzymes for advanced biofuels
production78. Petrobras, the Brazilian petro-giant, is also coordinating a number of
research projects along with research institutes to come up with findings along the same
lines.
109
Table 7.10 gives an overview of the major Brazilian biodiesel production facilities.
Table 7.10: Biodiesel Producers in Brazil
Producer Location Estimated Annual
Output (1000 t) Feedstock used
Soyminas Cássia/MG 12,0 sunflower and soybean oil
Agropalma Bélem/PA 8,1 palm oil
Brasil Biodiesel Teresina/PI 0,6 castor oil
Biolix Rolândia/PR 9,0 soybean
Brasil Biodiesel Floriano/PI 27,0 castor oil
NUTEC Fortaleza/CE 0,7 castor oil
Source: Workshop on Sustainable Biomass Production for the World Market, Sustainable
Bioenergy Trade, December 2005
7.3.2 Argentina
Argentina is another South American nation that has established itself as one of the
leading exporters of biodiesel. Interestingly, the Argentinean domestic market and its
laws governing biodiesel production are rather dis-organized. It therefore makes the
country’s biodiesel success all the more noteworthy. The country has 12 approved
biodiesel producers79, with a combined capacity of 1.5 million tons/annum. Almost all
of Argentina’s biodiesel is from soybean as the country enjoys bi-annual soy crops.
Argentina’s rise as a biodiesel exporter is further supported by its tiny domestic
biodiesel consumption. Even when the country’s mandatory B5 programme is put in
place80, current biodiesel producers in the country would need to run their plants at
only half their capacities to meet the demand. With newer plants getting go-aheads,
Argentinean biodiesel exports are expected to maintain a steady growth trajectory.
Future Roadmap
Despite restrictions to its exports from the EU, such as Germany’s restrictions to the
entry of soy-based biodiesel80, the country’s exports will continue to grow as soy-
based biodiesel and soy-meal are both highly in demand within the EU. To
strengthen its performance even more and help its domestic market, the Argentinean
government is contemplating the following measures:
Allowing biodiesel exporters to sell into the domestic market as well so as to
maintain plants at optimal operational loads. The recent global downturn has
had many producers producing significantly below their production capacities.
Finalizing a date for a national B5 mandate and,
Creating a Biodiesel Stabilization Fund that would help smoothen out domestic
biodiesel price fluctuations and help buffer any economic upheavals.
79. Argentina Biofuels Annual Report 2010, Global Agricultural Information Network,
http://gain.fas.usda.gov/Recent%20GAIN%20Publications/Biofuels%20Annual_Buenos%20Aires_Argentina_7-6-2010.pdf 80. State of the Argentine Biodiesel Industry, First Semester 2009 Report, Argentine Renewable Energies Chamber,
http://www.argentinarenovables.org/ingles/informes_estudios_ensayos.php
110
A brief overview of biodiesel production facilities in the country is shown in Table
7.11.
Table 7.11: Major Biodiesel Producers in Argentina
Producer Location Estimated Annual
Output (Tons/annum) Feedstock used
Renova San Lorenzo – Santa Fé 200.000 Soybean
Ecofuel San Martín – Santa Fé 200.000 Soybean
Vicentín Avellaneda – Santa Fé 47.500 Soybean
Emp Sanluiseña Energía Ar Vª. Mercedes – San Luis 30.000 Soybean
Biomadero Vª. Madero – Buenos Aires 72.000 Soybean
Soy Energy Vª Astolfi – Buenos Aires 32.400 Soybean
Adv. Organic Materials PIP – Pilar – Buenos Aires 15.800 Soybean
Louis Dreyfus Gral. Lagos – Santa Fé 300.000 NA. Plant Under
Construction
Patagonia Bioenergía San Lorenzo – Santa Fé 250.000 NA. Plant Under
Construction
Renova San Lorenzo – Santa Fé 200.000 NA. Plant Under
Construction
Unitec Bio -Eurnekian San Martín – Santa Fé
200.000 NA. Plant Under
Construction
Explora San Martín – Santa Fé
120.000 NA. Plant Under
Construction
Molinos Río de la Plata Rosario – Santa Fé 100.000 NA. Plant Under
Construction
Source: Argentine Potentiality to Develop Sustainable Bioenergy Projects, Energy Sustainability 2009
7.3 REGION 4: NORTH AMERICA
Unlike the rest of the world (barring Europe), North America is a major hub for biodiesel
consumption. The transportation sector alone accounts for more than 80% of all biodiesel
consumed. With time, the percentage may shrink, but volumes will continue to rise. The
two dominant markets in this region are that of Canada and the USA.
7.3.1 Canada
The Canadian biodiesel industry has been limited in its expansion. Even though the
government would like to see a 2% mandatory blend into commercial diesel81, high
prices of feedstock (canola and palm oil) and Canada’s primary dependence on
animal by-products have so far held back the country’s biodiesel output.
Thus, the mandate may not be met by domestic production alone. And with most
government policies leaning towards the promotion of ethanol, biodiesel output in
81. Canada Biofuels Annual Report 2009, Global Agricultural Information Network,
http://gain.fas.usda.gov/Recent%20GAIN%20Publications/General%20Report_Ottawa_Canada_6-30-2009.pdf
111
Canada currently remains at a state of crossroads. A list of the major biodiesel
producers in Canada is as under:
Table 7.12: Major Biodiesel Producers in Canada
Name Province Capacity
(tones / year) Feedstock
Ocean Nutrition Nova Scotia 7,000 Fish oil
Rothsay Quebec 35,000 Fats/used oil
Topia Ontario 15,000 Used oil
Biox (const.) Ontario 60,000 not known
Milligan Bio-tech Saskatchewan 4,500 Canola oil
Agrigreen Biodiesel British Colombia 2,000 Canola/used oil
Kyoto Fuels (const.) Alberta 33,000 Fat/used oil/ can. oil
Cal. Biodiesel (const.) Alberta 20,000 Used oil/tallow
Source: Biodiesel Production in the County of Newell, The Economic Development and
Tourism Department, Newell County, Canada
7.3.2 United States
The USA on the other hand is a hotbed for biodiesel production and consumption.
The potential for output expansion here is massive. The current administration is
firmly behind supporting alternatives to crude oil. It has extended generous financial
assistance, worth several million dollars82, on a number of occasions to spur both
research and production of biodiesel.
The US also happens to be the nerve centre of research in biodiesel feedstock and
production economics. It leads the world in algal biodiesel research and claims it to
be the future of biodiesel in the years to come.
Table 7.13 is a list of the major biodiesel producers in the US.
Table 7.13: Biodiesel Producers in USA
Name Location Capacity (Million
Tones / year) Feedstock
Delta Biofuels, Inc. Natchez, MS 80-100 Soybean
Cargill, Inc. Wayzata, MN 40 Soybean, Canola
Imperium Renewables, Inc. Seattle, WA 100 Canola, Soy
Western Dubuque Biodiesel, LLC Farley, IA 30 NA
Western Iowa Energy, LLC Wall Lake, IA 30 Soybean, Animal fat
Direct Fuels Euless, TX 10 Animal fat
High Plains Bioenergy Shawnee Mission, KS 30 Animal fat
Source: National Biodiesel Board (NBB)
82.
U.S. offers $790M to next-gen biofuels, Cleantech Group, http://cleantech.com/news/4429/us-offers-790m-next-gen-
biofuels-me
112
7.4 REGION 5: EUROPE
7.4.1 European Union
The European Union is the hotbed of the global biodiesel industry. Member states
put together, the EU is both the largest producer and consumer of biodiesel at the
same time. Germany, France and Italy are the three biggest producers with 76
percent of the total production. BENELUX (Belgium, Netherlands and Luxemburg)
and other new member states such as Spain, Austria and Greece have recently joined
the foray83.
After witnessing a strong production expansion from 2006 to 2008, EU biodiesel
output witnessed a slump in 2009 owning to a fall in global crude oil prices and
rising imports of US and Argentinean biodiesel. Production in 2009 was higher than
in 2008 by 9 percentage points, but the increase was lower than the one for 2008 over
200779. Table 7.14 shares an overview of EU’s biodiesel production trends:
Table 7.14: EU Biodiesel Production – Main Producers (million liters)
Calendar Year 2006 2007 2008 2009 2010 2011
France 650 1,310 2,370 2,610 2,610 2,610
Germany 2,730 3,280 3,250 2,870 3,410 2,500
Benelux 50 290 430 800 1,250 1,650
Spain 140 170 220 590 980 1,080
Poland 100 60 190 430 680 850
Italy 680 530 760 680 680 680
Others 1,010 1,180 1,590 1,630 2,090 2,220
Total 5,360 6,820 8,810 9,610 11,700 11,590
Source: EU FAS posts
Feedstock
Rapeseed oil forms the backbone of EU biodiesel. Other feedstock such as Palm Oil
and Soybean Oil are limited by DIN En 14214 as soy-biodiesel evidently does not
comply with the standard’s iodine value, and palm-oil is not particularly suitable for
cold Northern European temperatures.
The use of soybean oil has witnessed a bit of a slump after the imposition of
antidumping duties on US exported soy-biodiesel. Although offset by Argentinean
imports, which enjoy a preferential tax status, the use of soybean oil continues to
decline as manufacturers have been moving from B100 to B99 and larger blends.
Table 7.16 gives an overview of the feedstock use in EU over the recent years:
83. EU-27 Biofuels Annual Report 2009, Global Agricultural Information Network,
http://gain.fas.usda.gov/Recent%20GAIN%20Publications/General%20Report_The%20Hague_Netherlands-
Germany%20EU-27_6-15-2009.pdf
113
Table 7.16: Feedstock used for Biodiesel Production – 1000 MT
Calendar Year 2006 2007 2008 2009 2010 2011
Rapeseed oil 3,900 4,400 5,140 5,900 7,500 7,270
Soybean oil 400 700 950 770 740 750
Palm oil 120 250 530 540 660 740
Sunflower oil 10 70 170 250 250 250
Other virgin veg. oils 230 300 385 400 400 400
Recycled veg. oils 70 200 295 370 565 620
Animal fats 50 130 280 270 320 320
Other 30 35 40 40
Total 4,780 6,050 7,780 8,535 10,475 10,390
Source: EU FAS posts
Future Roadmap
Although biodiesel consumption will continue to rise, EU’s biodiesel output is
expected to stagnate in 2011. This is heavily influenced by Germany’s decision to tax
B100 and its gradual shift towards bio-ethanol (E10) in the near future. Since each
member nation of the EU is required by mandate to substitute at least 10% of its
transport fuel by renewables83, Germany seems to be favoring E10 and alternatives
like B7 for its mandate. Producers reportedly prefer using blends to B100 as it
involves easier handling and less bureaucracy.
Moreover, consumption bases will be shifting out from Germany France and Italy to
newer entrants such as Spain, Czech Republic and Poland. Also as the Sustainability
Certificate (SC) is imposed feedstock sources for biodiesel production (by early 2011,
starting with Germany), it remains to be seen if producing biodiesel from traditional
sources will be competitive in the future.
Table 7.17 highlights the major biodiesel producers in Europe.
Table 7.17: Major Biodiesel Producers in Europe
Country Production Facility / Site
Location
Production Capacity
(tons/annum) Feedstock Used
Germany BIOPETROL Industries AG 350,000 Rapeseed oil
Germany EcoMotion GmbH 200,000 Animal fats, waste cooking oil, rapeseed oil
Germany VERBIO Diesel Bitterfeld GmbH 200,000 Rapeseed oil, soybean oil, fatty acids
Germany Petrotec Biodiesel GmbH 185,000 Rape seed, soy and palm oil, yellow grease, animal fats, fish oils
Germany Mannheim Bio Fuel GmbH 10,000 Waste cooking oil, rapeseed oil
Austria Biodiesel International / Ventspils (Latvia)
100,000 Rapeseed oil, soybean oil
Austria Biodiesel Vienna / Oil port Lobau, Vienna
140,000 Various vegetable oils and used frying oil
114
Country Production Facility / Site
Location
Production Capacity
(tons/annum) Feedstock Used
Italy NOVAOL / Milano 250,000 Rapeseed, sunflower and soybean oil
Italy OXEM / Mezzana Bigli 200,000 Vegetable Oils
Italy Mythen 200,000 Vegetable Oils
Italy ITAL BI OIL S.r.l. / Monopoli 150,000 Rapeseed oil
Spain Infinita Renovables / Madrid 900,000 Soya, rapeseed and palm oil
Spain BioOils Energy / Madrid 250,000 Rapeseed, palm, soya, sunflower oil
Spain ACCIONA Energia / Navarra & Bilbao
70,000 Various vegetable oils
Spain Stocks Del Valles / Montmelo, Barcelona
31,000 Recycled vegetable oils, animal fats
Finland Neste Oil / Porvoo 170,000 Vegetable oils, animal fats
Switzerland Biopetrol Industries / Rostock and Schwarzheide, Germany Rotterdam, Netherlands.
840,000 Rapeseed oil
Sweden Perstorp BioProducts AB / Helsingborg
160,000 Rapeseed oil
Sweden SunPine AB / Piteå 88,000 Residues from pulp industries, such as pine-tree oil
Sweden Lantmännen Ecobränsle AB / Karlshamn
40,000 Rapeseed oil
UK Argent Energy / Motherwell, Scotland
45,000 Tallow and used cooking oil
France
Diester Industrie / Grand – Couronne, Le Meriot, Compiegne, Sete, Boussens, Montoire, Coudekerque, Bordeaux
2,150,000 Rapeseed, sunflower and other vegetable oils
France INEOS Enterprises Limited / Verdun
200,000 Various vegetable oils
France Biocar / Marseille 200,000 Various vegetable oils
France Centre Ouest Cereales / Chalanday
120,000 Various vegetable oils
France Daudruy / Dunkerque 150,000 Animal oil methyl ester
France SCA Petrole et Derives / Cornille 100,000 Animal oil methyl ester
France SARP Industrie / Limay 80,000 Recycled frying oil
Belgium OLEON NV / Port of Ghent 100,000 Rapeseed oil, recycled vegetable oils
DOW Haltermann / Kallo, Belgium
20,000 Rapeseed oil, recycled vegetable oils
Belgium Proviron Fine Chemicals NV / Oostende
100,000 Rape seed oil, sunflower seed oil, soybean oil and also used frying oils
Source: Main actors in biodiesel and bio-ethanol production in the EU, Biofuels Platform
115
EEccoonnoommiiccss FFoorr BBiiooddiieesseell PPrroodduuccttiioonn
8.1 KEY DRIVERS
Economics being a key driver for use of biofuels, very sound techno-economic
evaluation are one of the prime consideration for success and growth of any
biodiesel project. These evaluations are to be upgraded and revised with change in
process technologies, market fundamentals, strategic and other necessary variations
with time, place, climate and country.
Driven by growing volatility in global crude oil markets, biodiesel have become
targets of immense interest to investors and policy makers around the world. Based
on the business fundamentals, key public policy and strategic challenges, there is
need to efficiently exploit synergies that exist between agricultural resources and
energy needs in the biodiesel area.
It has physical properties similar to petroleum diesel, can be used individually or
mixed with diesel in diesel engines. Moreover, glycerin, a byproduct, can be used in
food, medical or cosmetic industries. Cake is also an important byproduct to improve
the economy with greater research and utilization.
Production of biodiesel can result in increased rural employment and economic
development and can provide additional markets for agricultural crops. However,
under current economic conditions, biodiesel may be more expensive than petro-
diesel.
Relative to petro-diesel, the higher cost of biodiesel reflects a variety of eco-nomic
realities associated with production of biodiesel, including the high cost of
feedstocks, as feedstock costs constitute 75%~85% of the total cost of biodiesel
production. The situation is aggravated by the high price volatility of these
feedstocks.
With present cost of biodiesel being higher than petroleum diesel, research is to be
done to work on a steady state design and improvements in the process technologies
to minimize and optimize the production costs, plant operations and to add value to
by products.
Studies are to be undertaken to reduce the
Cost of producing feedstocks and using cheaper varieties.
Cost of manufacturing biodiesel.
Securing long-term product purchase agreements for biodiesel.
Investment uncertainties and risks.
The key drivers promoting development of the biofuels market are the same for
energy generally:
CCHHAAPPTTEERR 88
116
Concerns over security of supply (biofuels allow a more diversified mix)
Climate change (carbon emissions are less than burning fossil fuels), and cost
(although reliant on subsidies currently, the expectation is that with carbon
taxes eventually factored in, biofuels will be cost competitive).
Tax and subsidy regimes in different countries continue to play role in
development of the biofuels industry.
It can be stated that biofuel economics depend heavily on following main factors:
Availability of land at the right climate
Technology development
Government policies
The data and the research findings about biodiesel and its potential for development
vary somewhat across different organizations, academics and Government entities.
Main reasons for variations are
Rapidly increasing interest in biodiesel;
Largely unregistered and unreported biodiesel production, estimated
indirectly from other data, such as oil imports;
Ongoing development of government policies and procedures to properly
regulate this industry
Vegetable oil, hence oil seed, is the main raw material used in producing biodiesel.
Cost of biodiesel as raw product was estimated as 720$/ton in 2007 in Turkey84. This
figure was $200/ton higher than petroleum based raw product cost, it was stated to
be still considerably less than the fully taxed petroleum based diesel.
8.2 AGRICULTURAL AND PRODUCTION ISSUES
The biodiesel supply-chain consists of 3 major steps:
Cultivating oil seed
Producing vegetable oil
Producing biodiesel
8.2.1 Agricultural Processes84
Agricultural process encompasses all of supply-chain activities related to growing
the oil seed crop for production of biodiesel.
84. Kleindorfer, P.R. & Oktem, U.G. Economic and Business Challenges for Biodiesel Production in Turkey,Sept 2007
117
Figure 8.1: Flow Diagram of Agricultural Process
The growth rate of agricultural crop depend heavily on the information and training
provided to the farmers as well as available government support. Farming in India is
small family business which involves growing crops in smaller fields than in US or
EU.
Farmers do not research what to plant to get the best return from their fields. Usually
they plant the same crop as their neighbor. The Government uses to purchase large
amount of farm products at a given price.
With biofuels, a balance has to be struck in providing government support between
and rapid development of the industry.
Breakdown of the oil seed production cost factors is as follows:
Initial turning over of the land
Smoothing and fertilizing
Sowing equipment rental
Seed
Fertilizer (cost of fertilizer varies depending on the quality of the ground and
type of crop)
118
Harvesting
Agricultural chemical applications for disease and pests
The cost of the land is an important factor. The land is divided into small, varying
size fields due to inheritance, making industrial scale production with machinery
rather inefficient cost wise
Before making a recommendation concerning whether a crop would be an efficient
crop, either as a primary crop or as a rotational crop, one needs to consider the
economics of alternative crops in a given environment.
For example, as one can see from the comparison of canola with corn given in Table
8.1 for Turkey, under the current circumstances, a farmer who can grow corn would
not find it profitable to switch to canola. This is true even though the cost of planting
and harvesting canola seed is considerably less than for corn.84
Table 8.1: Illustrative Profitability of Canola vs. Corn (At Estimated 2006
Prices and Yields)
8.3 MANUFACTURING PROCESSES
The model encompasses major steps of supply-chain for producing biodiesel from oil
seed. The process of manufacturing biodiesel from oil is made up of two completely
separate manufacturing systems:
producing oil from the seed, and
producing biodiesel from oil.
119
8.4 EXAMPLE OF OIL PRODUCTION FROM CANOLA
Canola seed contains about 40% oil. The remainder is processed into canola meal,
which is used as a high protein livestock feed. Research indicates the fatty acid
composition of canola oil is most favorable in terms of health benefits and as a part of
a nutritionally balanced diet. (Canola council of Canada) Hence, canola is used in
many food products and for cooking, and its competing use for biodiesel could
therefore have a strong impact on vegetable oil markets in the food industry. This
will create added complexity in managing a biodiesel business because of competing
oil-for-food and oil for-biodiesel prices.
For example, if price in vegetable oil markets exceed the price of canola oil for
biodiesel, producers can sell the raw material (vegetable oil) as is rather than
converting. This may cause problems for distributors of biodiesel products who may
not want to get into long-term contracts. Such a scenario would also upset biodiesel
manufacturers’ plans dramatically; reducing profits and extending the capital cost
recovery period.
Let us briefly summarize the canola oil production process from canola seed to
purified canola oil.
These steps are very similar for most vegetable oil production processes:
First stage is rolling or flaking the seed. This will crack the cells and facilitate oil
extraction.
Next stage involves cooking the rolled or flaked seeds and subjecting them to a
mild pressure which squeezes out some of the oil and compresses the seeds into
large chunks of cake fragments.
Cake fragments are further processed to extract most of the remaining oil.
Once the solvent used for extraction is removed and recovered the oil undergoes
purification processes.
Degumming consists of removal of gums (phosphatides) and free moisture, and
cooling/storage of dry oil.
The next refining steps are: neutralization of fatty acids, drying (removing of traces
of water), bleaching by adsorption of the color producing substances, and
deodorization through vacuum steam distillation.
8.5 BIODIESEL PRODUCTION
Currently almost all biodiesel is produced using base catalyzed trans-esterification of
the oil. This process requires low temperatures and pressures and has about 98%
conversion yield. The main processing steps are as follows:
Reaction:
Mixing of alcohol (usually methanol) and catalyst (typically anhydrous
sodium hydroxide).
Adding oil and (sometimes) heating the mix.
Separation of biodiesel and glycerin phases
Alcohol removal from each phase
120
Glycerin neutralization by using an acid to neutralize unused catalyst and soaps.
Preliminary removal of water and alcohol yields 65% (low purity) glycerin
(appropriate for mixing with animal feed) which can be further purified by
distillation to 99+% purity and sold to the cosmetic industry.
Biodiesel purification (sometimes) by washing, with warm water, to remove
residual catalyst or soaps. Sending to storage after drying.
There are many small biodiesel manufacturing facilities that can probably meet the
needs of the local population. Large biodiesel facilities to serve the needs of major oil
companies are very few, but this appears to be a promising business with the
decision to encourage the use of biodiesel.
With favorable economics and increasing demand, both to lower petroleum
dependency and to market, it seems that country should invest in developing this
technology.
Similar to Brazil, India can become not only a significant biodiesel producer but also
a technology developer and implementer targeting other countries in the process.
Investing in the new generation production process which would use solid catalysts
and hence reduce the production cost significantly while enhancing the purity of the
products presents additional opportunities.
Figure 8.2: Flow Diagram for Biodiesel Production
121
8.6 OVERALL COST AND ENERGY CONSUMPTION85
Following Figure classifies the average operating costs for the biodiesel process. It
shows that the energy cost did not play an import role on the total cost as much as the
cost of the reactants, methanol and palm oil. The sharing of the energy cost is only 5%
while the cost of palm oil and methanol had the sharing of 80% and 15 %, respectively.
One possible reason is that the reactions are exothermic reactions, which increase the
temperature of the reactor by itself, so the heat for the reactors is not as much as
required. The other reason is that if compare prices per unit, the price of energy (3 Baht
/unit) is about 7-8 times lower than price of palm oil (20-25 Baht /kg). Therefore, if the
price of oil is lower, the operating cost of methyl ester also decreases.
Figure 8.3: Average percentage of varied costs in the process
Average percentage of energy distribution in each unit operation of the process is
shown below. It is seem that most energy was consumed by the methanol recovery
unit (66%) such as from the distillation column and the rest was used by the reactor
(17%), evaporator (to evaporate water from methyl ester (11%) and preheating the
reactants before feeding to the process (6%).
Figure 8.4: Average percentage of energy distribution per unit operation
85. Kulchanat Kapilakarn & Ampol Peugton, Comparison of Costs of Biodiesel Production from Transesterication;
International Energy Journal 8 (2007)
122
8.7 ECONOMICS FOR PRODUCTION OF BIO DIESEL IN CANADA USING
CANOLA
Daniel Bieber et al have conducted a very good studies to produce 17 MM litres per
year of biodiesel by converting triglycerides from waste cooking oil and greenseed
canola in a continuous process86.
The plant consists of three main sections; a canola crushing plant, a biodiesel
conversion stage and finally a biodiesel/glycerol separation stage. The canola crushing
stage uses a screw press to extract 75% of the oil from the canola seed and a membrane
separator to extract the remaining 25% maximizing oil recovery and also will produce
a valuable meal. The biodiesel conversion stage uses a solid acid catalyst, zinc
ethanoate supported on silica to achieve 95+ conversion in a fixed bed reactor. Finally
gravity separators are proposed used to separate biodiesel from glycerol.
A conservative economical analysis found that the capital cost for the entire plant
was MM $2.8. Using a 10% discounted rate, the net present value of the plant could
be MM $5.3 after 10 years of operation, giving a discounted cash flow rate of return
of 49%.
This concludes that the plant could produce biodiesel on a scale to be competitive
with conventional diesel.
8.8 PRODUCTION OF BIODIESEL FROM JATROPHA CURCAS OIL BY
USING PILOT BIODIESEL PLANT87
Salient features of the pilot biodiesel plant as presented by Bulk Agro (India) Pvt.
Ltd. Are stated below. The cost of raw oil appears to be on lower side. Hence the
biodiesel price appears lower.
Simple in operation
Low cost technology
Shorter reaction time
Economics of biodiesel production
Cost of raw jatropha oil = Rs. 22/litre
Biodiesel processing cost = Rs. 9/litre
Cost of production = Rs. 31/litre
Less return from crude glycerol = Rs. 3/litre
Net cost of production = Rs. 28/litre
Dealers margin = Rs. 1/litre
Profit = Rs. 3/litre
Sale price of biodiesel = Rs. 32/litre
86. ChE 422, Design Report, Continuous Production of Biodiesel, Date Due: April 7, 2008, Department of Chemical
Engineering, University of Saskatchewan 87. Deepak Sain, Production of Biodiesel from Jatropha Curcas oil by using Pilot Biodiesel Plant, Bulk Agro (India) Pvt. Ltd.
123
8.9 ECONOMIC CONSIDERATIONS FOR A TYPICAL USA LOCATION88
In general, the larger the processing facility for biodiesel production, the lower the
per-unit capital and operating costs are involved. For larger capacity, the market has
to be developed enough at the time to warrant construction of large-scale facilities in
the location or the surrounding region. The following table indicates the impact of
econo-mies-of-scale on both the capital and operating costs for biodiesel facilities.
Table 8.2: Comparison of Estimated Capital Costs
8.10 CRITICAL COST BENEFIT ANALYSIS OF OILSEED BIODIESEL IN
CANADA89
Based on the analysis costs and benefits are presented to accrue in a number of
sectors and subsectors with the implementation of biodiesel manufacture in Canada.
Affected sectors would include seed production, farming, farm chemicals, fertilizer,
grain storage, grain transportation, crushing, biodiesel manufacture, biodiesel
distribution, petroleum manufacture and distribution
Similar economic studies need to be carried for India using nonedible oil sources for
biodiesel.
Canadian producers generate far more foodstuff than can be rationally consumed as
food by the populace. This resource of productive capacity is likely to be the basis of
grain crop based energy production. A portion of Canadian overproduction capacity
can readily and perhaps profitably diverted to domestic energy markets including
biodiesel.
88. Winrock International, Establishing Biodiesel Production Facilities in Arkansas, Submitted to USDA/Rural Business –
Cooperative Service, April 2004 89. Reaney, M.J.T., et al., A Critical Cost Benefit Analysis of Oilseed Biodiesel in Canada, A BIOCAP Research Integration
Program Synthesis Paper
124
The goal of study was to explore the resources in Canada that might be converted to
biodiesel and through cost benefit analysis, determine those strategies that are likely
to be more profitable and sustainable. In this study biodiesel threads are explored
from farm production of seed to consumers.
Costs and benefits of elements of the thread include
Producer margins to determine the costs and benefits of growing biodiesel
crops.
Grain transportation and storage implications of various feed materials. 3) Oil
extraction and refining strategies that impact on non-oil co-products. 4)
Biodiesel production technology
Distribution of biodiesel to the consumer.
8.11 A PRELIMINARY ECONOMIC FEASIBILITY STUDY COMMERCIAL
BIODIESEL PRODUCTION IN SOUTH AFRICA90
Calculations have been made to assess the financial feasibility of commercial
biodiesel production based on a 2500 kg/h (22.5 million litres/annum) plant.
The size is based on findings of Amigun & von Blottnitz (2005) that the optimum
biodiesel plant size in South Africa ranges between 1500 and 3000 kg/h.
Two types of plants were considered, namely a seed extraction biodiesel production
(SEBP) plant using locally produced oilseeds as feedstock and a crude oil biodiesel
production (COBP) plant using imported crude vegetable oil as feedstock.
The capital investment for a SEBP plant ranges between R110 and R145 million while
a COBP plant would require a capital investment of about R45 to R50 million. These
amounts include a working capital of about R35 million due to money that is fixed in
a 3 month stock supply.
The calculated biodiesel manufacturing costs of the two types of plants for various
feed stocks at prices in August 2006 are shown in Table 8.3.
Table 8.3: Manufacturing costs of biodiesel for various feed stocks
90. Mirco Nolte, Commercial Biodiesel Production in South Africa: A preliminary economic feasibility study, MS Chemical
Engineering thesis, University of Stellenbosch, March 2007
125
Feedstock and raw material contribute to about 80% of the manufacturing cost while
transport costs are the second biggest contributor. These results point to the fact that
the plant location is very important in order to minimize production costs.
Commercial biodiesel production should not be centralized, but should rather
happen through greater number of relatively small plants located in oilseed
producing regions.
The sensitivity analyses showed that the manufacturing costs of a SEBP plant are
very sensitive to changes in oilseed and oilcake prices while the manufacturing costs
of a COBP plant are very sensitive to a change in crude vegetable oil price.
The fluctuating nature of the agricultural commodity prices makes biodiesel
manufacturing costs unpredictable. Soybean biodiesel costs are the most sensitive to
price changes while sunflower biodiesel costs are the least affected.
An increase in glycerol price would decrease the manufacturing costs of biodiesel by
about 12 cents/litre for every R1000/ton increase in price. Glycerol prices are
currently too low to consider in the calculations due to a global oversupply as a
result of biodiesel production.
The break even price of biodiesel have been calculated.
8.12 NEW AND DEVELOPING PROCESSES TO IMPROVE ECONOMY
Research and development is taking place relentlessly to find better and cheaper
ways to produce biodiesel. Few of the developments are discussed below
8.12.1 Waterless biodiesel promises greater efficiency91
Greenline Industries rake in $20m to support expansion of ion resin catalyst-based
technology that replaces water in refining process, improving biodiesel's power and
curbing water use
A series of reports have warned that water-intensive biofuel refinery and agricultural
processes could contribute to water scarcity. A study last year from the National
Research Council warned that increased demand for water through energy crop
irrigation and biofuel production could result in a serious drought risk in coming
years.
The company's biodiesel production process uses an ion resin catalyst to purify the
biodiesel, rather than the more traditional process of washing it with water.
Water can be a problem during biodiesel production, because residual water in
biodiesel fuel can make it more difficult for the fuel to combust, reducing its power.
91. Danny Bradbury, "Waterless" biodiesel promises greater efficiency, businessGreen, 09 Apr 2008, Available at:
http://www.businessgreen.com/bg/news/1800780/-waterless-biodiesel-promises-efficiency
126
8.12.2 Membrane Technology in Production of Biofuels92
The time-tested membrane filtration technology is being adopted for future
biofuels and integrated biorefineries Table 1 provides a brief listing and overview
of KMS experience in membrane filtration applications.
Using membrane technology has the potential to greatly reduce operating costs
compared to the traditional method of using an evaporator to recover or remove
water, which requires very high energy use.
8.12.3 New biodiesel process93
NExBTL technology is the outcome of manufacturing tests that begun in the mid-
1990s, and an R&D programme launched in 2001.
One of the major strengths of the new technology, from a production point of view,
is that it can use either vegetable oil or animal fat as its raw material. This enables
input to be sourced both flexibly and cost-effectively. Not only that, the quality of the
end-product fuel is very consistent, and free from the quality fluctuations typical of
the methyl ester sold as biodiesel.
In addition to consistent quality, Neste Oil’s biodiesel offers good cold tolerance and
storage properties, a high cetane number, and extremely low exhaust emissions. The
good performance of NExBTL biodiesel at low temperatures, an area where methyl
ester-type biodiesels normally come unstuck, is a particular advantage.
A €100million, 170000t/y plant was known to be constructed at Porvoo in Finland
and to showcase the new technology.
8.13 REDUCTION IN COST FOR BIODIESEL FROM ALGAE
One of the problems with current methods for producing biodiesel from algae oil is
the processing cost, and the New York researchers say their innovative process is at
least 40 percent cheaper than that of others now being used. Supply will not be a
problem: There is a limitless amount of algae growing in oceans, lakes, and rivers,
throughout the world.
Another benefit from the "continuously flowing fixed-bed" method to create algae
biodiesel is that there is no wastewater produced to cause pollution.
"This is economical way to produce biodiesel from algae oil," according to lead
researcher Ben Wen, Ph.D., vice president of United Environment and Energy LLC,
Horseheads, N.Y.
It may cost less than conventional processes because of the need of smaller factory,
no water disposal costs, and the process is considerably faster.
92. WaterWorld Online, October 2010, Membrane Technology in Production of Biofuels 93. EngineerLive, New biodiesel process overcomes hydrogen technical problems, Available at:
http://www.engineerlive.com/Process-
Engineer/Renewables/New_biodiesel_process_overcomes_hydrogen_technical_problems/14269/
127
A key advantage of the new process is that it uses a proprietary solid catalyst instead
of liquid catalysts. First, the solid catalyst can be used over and over. Second, it
allows the continuously flowing production of biodiesel, compared to the method
using a liquid catalyst. That process is slower because workers need to take at least a
half hour after producing each batch to create more biodiesel. Batch process need to
purify the biodiesel by neutralizing the base catalyst by adding acid. No such action
is needed to treat the solid catalyst.
It is estimated that algae has an oil-per-acre production rate 100-300 times the
amount of soybeans, and offers the highest yield feedstock for biodiesel and the most
promising source for mass biodiesel production to replace transportation fuel.
Depending on the size of the machinery and the plant, it may be possible that a
company could produce up to 50 million gallons of algae biodiesel annually.
Solid catalyst continuous flow method can be adapted to mobile units so that smaller
companies wouldn't have to construct plants and the military could use the process
in the field.
8.14 CONCLUSION
A complete comprehensive economic analysis has to done to show the likelihood of a
strong potential for profitability.
Many alternatives need to be considered, and the plant always should sustain
enough income to generate a net positive cash flow.
128
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9.1 RESEARCH ON APPROPRIATE FEED STOCK SOURCES FOR
BIODIESEL
The biodiesel production may be from edible or nonedible oils. The source of
Biodiesel usually depends on the crops amenable to the regional climate. Depending
upon the geographical locations and various other factors, the commonly used oils
for the production of Biodiesel are Jatropha, canola, soybean, sunflower, palm,
rapeseed, cotton seed etc.
In the United States, soybean oil is the most commonly Biodiesel feedstock, whereas
the rapeseed (canola) oil, Jatropha oil and palm oil are the most common source for
Biodiesel, in Europe, and in tropical countries.
The use of plants and plant products – among others – as replacement of
conventional fuels is an excellent option. But it depends on sufficient knowledge
regarding the plant’s relationship with its environment.
Bio energy production may be restricted to otherwise uncultivable land. Knowledge
defining appropriate plants, cultivation systems and general agronomic practices to
utilize these abandoned lands is a prerequisite for future success.
Life cycle studies for J. curcas need to be undertaken. Unlike other energy plants,
Jatropha, when planted on wastelands and degraded lands, does not interfere with
food security in food-insecure countries. Such studies will only enable the realization
of proper accounting of the impact on carbon benefits (soil and plant organic carbon
stores).
The yield and quality of the oil from seeds of the non-toxic genotype of Jatropha are
similar to those of the toxic genotype. Studies for a comparative evaluation of the
two genotypes for their seed yield and disease susceptibility should be conducted.
Selection, breeding and agronomic studies for both genotypes need to be undertaken.
Various bioactive moieties and their pharmaceutical and biological effects appear to
have been reported using the toxic genotype of Jatropha. It would be interesting to
examine the presence of activities in various parts of the non-toxic Jatropha.
The oil from the toxic genotype could be freed of phorbol esters using the
deodorisation or stripping process, an oil pretreatment process, during the process of
biodiesel production. The deodorization/ stripping process could be optimized to
obtain oil free of phorbol esters.
So it may be desirable to focus research on four fields including plant breeding,
development of cultivation techniques, processing technology, and by-product
utilization.
CCHHAAPPTTEERR 99
129
Researches done by researchers in plant breeding and cultivation have resulted in the
improvement of jatropha productivity by 60% (from 5 to 8 tons /ha/year) through
the improved population method. Jatropha plant breeding are to be focused on the
use of genetic engineering to improve jatropha productivity level up to 15
tons/ha/year and to result in synchronized harvest In order to develop jatropha as a
commercially profitable commodity.
Research collaboration with institutions in countries concerned with up-stream to
down-stream jatropha development is necessary. Researches in the utilization of
jatropha seed meal processing into bio-pellet, bio-briquette, biogas, and compost may
be required.
9.2 THERE IS NEED TO CONDUCT DEVELOPMENTAL RESEARCH ON
IMPROVED TECHNOLOGIES BASED ON UNCONVENTIONAL NON
EDIBLE FEEDSTOCKS
Research using cooked and waste oil, algae, oil sludge to improve trans-esterification
may be intensified.
Algae have drawn considerable interest as a renewable source. A pulsed-electric-
field (PEF) pre-treatment technology to facilitate extraction of oils from algae cells as
introduced recently by Diversified Technologies Inc. (Bedford, Mass.;
www.divtecs.com) needs to be developed.
Process on in – situ trans-esterification of seed may be researched for biodiesel
production.
Investigations are to be done to develop process for producing biodiesel by first
extracting lipids from the sludges generated during primary and/or biological
treatment of municipal, agricultural, and industrial wastewaters using primary,
secondary, and tertiary treatments followed by the trans-esterification of the
extracted lipids using trans-esterification conversion into alcohol-based esters.
9.3 ACID AND BASE HOMOGENEOUS CATALYSTS
Transesterifiation is reversible reaction. Several aspects having influence on the
reaction and process technology need to be developed further by concerted research
efforts. Typical aspects are discussed below for catalytic processes on biodiesel
production.
9.3.1 Alkooxide Catalysts
Alkali, Acid and Biocatalyst can be used in trans-esterification.
Alkaline metal hydroxides, such as KOH and NaOH, are cheaper than metal
alkoxides, but less active.
It may therefore be of benefit to develop highly active metal alkoxides at cheaper
price for continuous development of the process.
130
9.3.2 Typical Benefits and Drawbacks of Base catalysts
The acidic catalysts, sulfuric or sulfonic acid are less active than basic catalysts and
are highly corrosive.
Most of the biodiesel produced is made with the base catalyzed reaction for the
reasons that
It works low temperature and pressure.
It yields high conversion (98%) with minimal side reactions and reaction time.
It allows a direct conversion into biodiesel with no intermediate compounds
and requires simple construction materials.
Typical drawbacks of the alkaline catalytic process are as follows:
Energy intensive,
Recovery of glycerol difficult
Alkaline catalyst has to be removed from the product
Alkaline wastewater requires treatment
FFAs in feed and water interfere with the reaction
Research is therefore required to be done to minimize and overcome the drawbacks
and improve the benefits of alkaline catalysts.
9.3.3 Various operation parameters
Different important parameters have to be researched and developed for
optimization of the technology. Some of them are discussed. Effect of catalyst
concentration for better applications in the process is as stated below.
9.3.3.1 Effect of alkaline catalyst concentration
Experimental results showed changes in ester yield content with varied catalyst
concentration. As the sodium hydroxide concentration increased, the conversion of
triglyceride as well as the ester content is also increased.
Insufficient amount of sodium hydroxide results in incomplete conversion of
triglycerides into the esters as indicated from its lower ester content.
In an specific case, the ester content reached an optimal value when the sodium
hydroxide concentration reached 1.5 wt.%. With further increase in catalyst
concentration, ester production decreased.
Large amount of soap was observed with excess amount of sodium hydroxide added
experiments.
This is because addition of excess alkaline catalyst caused more triglycerides’
participation in the saponification reaction with sodium hydroxide, resulting in the
production of more amount of soap and reduction of the ester yield so the catalyst
concentration optimization needs attention of researchers.
131
9.3.3.2 Acid catalyst trans-esterification
An alternative process uses acid catalyst that some researchers have claimed are
more tolerant of free fatty acids.
If more water and free fatty acids are in triglycerides, acid catalyst can be used.
It is known that trans methylation occur approximately 4000 times faster in the
presence of an alkali catalyst than those catalyzed by the same amount of acidic
catalyst.
Possibilities of more active, better, less corrosive, cheaper, long lasting catalysts
acidic or basic in nature, to be explored either in homogeneous or heterogeneous
modes. Heterogeneous catalysts may be supported on different kinds of supports
having high surface area, pore volume and other suitable physicochemical
characteristics.
9.3.3.3 Alcohol to vegetable oil molar ratio,
For enhancing forward reaction. large excess of methanol is used with base catalysts.
So steps are needed to modify parameters for minimizing methanol concn.
9.3.3.4 Temperature
Temperature, pressure and residence time may vary for different stocks and need to
be researched, optimized and modeled.
9.3.3.5 Purity of the reactants (mainly water content), and free fatty acid content
effect on trans-esterification
It is common for oils and fats to contain trace amounts of water. When water is
present in the reaction, it generally manifests itself through excessive soap
production.
Free fatty acids and water always produce negative effects since the presence of free
fatty acids and water cause soap formation, consume more catalyst, and reduce
catalyst effectiveness.
At high temperatures, it can hydrolyze the triglycerides to diglycerides and form a
free fatty acid.
The soaps of saturated fatty acids tend to solidify at ambient temperatures, so a
reaction mixture with excessive soap may gel and form a semisolid mass that is very
difficult to recover.
A number of researchers have worked with feed stokes that have elevated FFA
levels.
Waste greases typically contain from 10 to 25% FFAs. This is far beyond the level that
can be converted to Biodiesel using an alkaline catalyst.
132
Better methods for drying of feed stocks and removal of FFA need to be investigated.
The effect of above parameters is to be studied and optimized. Possibilities of having
antagonist for the side reactions be explored.
9.4 HETEROGENEOUS CATALYSTS, CONTINUOUS PROCESS
Heterogeneous catalysts are promising for the trans-esterification reaction of
vegetable oils to produce biodiesel. Unlike homogeneous catalysts, heterogeneous
catalysts are environmentally benign and can be operated as continuous processes.
Moreover, they can be reused and regenerated. The use of catalyst supports such as
alumina, silica and zinc oxide could improve the mass transfer limitation of three
phase reactions.
Furthermore, by anchoring metal oxides inside pores, catalyst supports could
prevent active phases from sintering in the reaction medium. Solid catalysts
eliminate the need for water washing, reducing waste water from plants. However,
this kind of process normally requires high pressure and temperature. This leads to
the decomposition of glycerol and other negative side effects.
Nevertheless, one of the major problems associated with heterogeneous catalysts is
the formation of three phases with alcohol and oil which leads to diffusion
limitations thus lowering the rate of the reaction [Annexure 6]
One way of overcoming mass transfer problem in heterogeneous catalysts is using
certain amount of co-solvent to promote miscibility of oil and methanol and
accordingly accelerate the reaction rate.
Studies have to be carried out to synthesize and develop new solid catalysts for
trans-esterification reaction in order to overcome some of the disadvantages of use of
homogeneous catalyst and more likely to reduce the cost of biodiesel production and
no fast deactivation of catalyst.
Commercial continuous biodiesel production process, using solid catalyst are to be
investigated that do not require any post treatment to remove the catalyst from
biodiesel and methyl ester yields, close to theoretical value, that could be achieved at
high pressure and temperature.
9.5 DEVELOPMENT OF ENZYMATIC CATALYSTS
Better catalysts and process steps are needed to be developed for overcoming various
problems of trans-esterification by homogeneous and heterogeneous catalysts.
The use of lipase is a great viable method for production of ester from different
sources of oil or grease. Research on this topic is still in progress due to the enzyme
flexibility and adaptability to new process
133
Enzymatic catalysis are very costly but have following benefits:
Enzymatic catalysts like lipases are able to effectively catalyze the trans-
esterification of triglycerides in either aqueous or non-aqueous systems.
Byproduct, glycerol, can be easily recovered with simple separation processes.
Enzymatic catalysts are often more expensive than chemical catalysts, so
recycling and reusing them is often a must for commercial viability.
Research is needed to bring down the cost for such enzymatic catalytic technologies.
9.6 SEPARATION OF PRODUCTS
Biodiesel reaction product needs to separated properly from the stream containing
other materials.
It is to be ensured that the following important factors are satisfied in the biodiesel
production process by trans-esterification:
complete trans-esterification reaction,
removal of glycerin
removal of catalyst
removal of alcohol
complete esterification of FFAs.
There is a need to develop low cost methods for recovery of products and use
unconverted streams. Methanol recovery and recirculation is an important parameter
to be developed.
9.7 REACTOR MODIFICATION
Study is needed to look into the possibilities for the development of modified
reaction and separation equipments for continuous production of bio diesel and its
purification like centrifugal contactors etc.
Static Mixers, laminar flow reactor/separator, Micro-channel Reactors. Oscillatory
flow reactors, Cavitational reactors, Rotating/spinning tube reactors, Membrane
reactors, reactive distillation, as discussed in chapter 5 need to be investigated
intensively by the researchers for better process development.
9.8 SUPERCRITICAL METHODS
Noncatalytic and Catalytic Supercritical process- One and Two Step Approaches
need attention of the researchers.
To overcome various drawbacks in the conventional alkali-catalyzed method, two
novel processes have been developed employing non-catalytic supercritical methanol
technologies and need further studies and directions.
134
Supercritical trans-esterification method is more tolerant to the presence of water and
FFAs than the conventional alkali-catalyzed technique, and hence more tolerant to
various types of vegetable oils, even for fried and waste oils.
The one-step method could produce biodiesel through trans-esterification of oils/fats
in supercritical methanol with simpler process and shorter reaction time. In addition,
a higher yield of FAME was achieved due to simultaneous conversion of FFA
through methyl esterification.
The two-step method, on the other hand, may realize more moderate reaction
conditions than those of the one-step method.
Further effort is to be made to develop an alternative method through the two-step
preparation; hydrolysis of triglycerides in subcritical water and subsequent methyl
esterification of fatty acids (FA) in supercritical methanol.
Catalytic supercritical methods should be explored for biodiesel production.
Esterification is catalyzed by solid strong acids to manufacture biodiesel.
Columns of chemically active solids to separate mixtures of chemicals, could be used
to make biodiesel Under the right conditions in the column, the oil and alcohol were
converted into biodiesel in few seconds only.
9.9 ADSORBENTS IN BIODIESEL PRODUCTION
Invention of adsorbent materials to purify biodiesel to provide a biodiesel product
with improved stability, acceptable for use as a fuel is to be investigated. Such
adsorbents may be magnesium silicate, magnesium aluminum silicate, calcium
silicate, sodium silicates, activated carbon, silica gel, magnesium phosphate, metal
hydroxides, metal oxides, metal carbonates, metal bicarbonates, sodium sesqui
carbonate, metal silicates, bleaching clays, bleaching earths, bentonite clay, and
alumina.
9.10 SIMULATION, MODELLING AND PROCESS OPTIMIZATION
Considerably increased interest in biodiesel production is being observed. Process
design and engineering, related to optimization of the process parameters to improve
the product quality, economics of operation, reduced downtime, faster rate of
production etc. is motivating researchers and the industry to address all aspects
related to its production. Attention must be paid in this area for the technology
improvement to derive better returns.
9.11 VALORIZATION OF BY PRODUCTS
While producing biodiesel, cake and glycerol are the important byproducts. They
have to be converted or treated in such a way that they yield valuable materials such
as proteins, surfactants, chemicals etc.
135
Figure 9.1: Existing and new natural oil processing mill improvement pathways
to chemicals
Specific features of the further research for the production of biofuel, protein
concentrates as livestock feed and value-added products that could enhance the
economic viability of oil-based biodiesel production are highlighted. The proposed
research will go a long way in helping the fuel crisis for the generation to come.
Possibilities are to be researched for making valuable protein based surfactants and
carbohydrate based chemicals from cake.
In conclusion, it is to be understood that although considerable progress has been
made in developing the process technologies for the production of biodiesel, yet
scope remains for further research to make the process not only more efficient
thermodynamically but also to improve the economics of production. At the same
time, the discovery or understanding of new feed materials would also arise and
adaptations will have to be made in the processes for this purpose. The information
given in this report is expected to be of interest to research scientists and engineers to
understand the directions in which research has been conducted and to focus their
research in a novel manner.
