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Bio-diesel Production using

Heterogeneous Catalyst

A K GUPTAINDIAN INSTITUTE OF PETROLEUMDEHRADUN, INDIA

XIII Refinery Technology Meet (RTM)

November 14-16, 2005, Hyderabad

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Commercial Biodiesel

Technologies

Currently used technologies for producing biodieselcan be classified into three categories:

1) Base catalyzed transesterification with refinedoils

2) Base catalyzed transesterification with low fattyacid greases and fats

3) Acid esterification followed by transesterificationof lower or high free fatty acid fats and oils.

Other processes under development include –

biocatalyzed transesterification, pyrolysis of vegetableoil/ seeds and transesterification in supercritical

methanol.

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The goal of all technologies is to produce fuelgrade esters meeting standard specifications(e.g. ASTM/ European/BIS).

The key quality control issues involve :

- complete (or nearly complete) removal of alcohol,catalyst, water, soaps, glycerine and unreacted or

partially reacted triglycerides and free fatty acids(FFA).

Failure to remove these contaminants causes the biodieselto fail one or more fuel standards.

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Problems of Biodiesel Production

Both base and acid catalyzed processes are associated withseveral inherent problems:

Free fatty acids interfere with transesterification deactivate thebase catalysts – loss of catalyst and biodiesel yield.

Water deactivates both basic and acidic catalysts. Drying ofoil may be required.

Soaps formed with base catalyst, form emulsion and foam anddifficult to remove.

When processing feed stocks with high free fatty acidsadditional steps must be taken.

After basic transesterification, the purification and adequatetesting during processing is required to produce fuel gradeesters.

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Appropriate Technology

The selection of appropriate technology for

production of bio-diesel requires careful

selection of processing steps, catalyst and

downstream process integration. The quality offeed vegetable oil particularly FFA content plays

and important role in identifying the suitable

technology.

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The important factors to be consideredinclude:

Must be able to process variety of vegetable oils withoutor minimum modifications.

Must be able to process high free fatty containingoils/ feed stocks.

Must be able to process raw both expelled and refined

oil. Process should be environment friendly almost zero

effluents.

Able to produce marketable by products glycerin, fatty

acids, soap if any. Must be able to produce fuel grade esters; Biodiesel

produced should meet the standard specifications.

The process should be adaptable over a large range ofproduction capacities.

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Feedstocks in Indian Context

For India non-edible oils obtained from plantswhich can be grown on waste/ semi arid lands

are more suitable. Species can be selectedbased on the regional climatic conditions

Most of the non-edible oils available in India

contains high FFA (2-12%)

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IIP Heterogeneous Process

for Bio-diesel Production

Reference Patents: US 2007282118

EP 1711588

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http://slidepdf.com/reader/full/rtm1 9/21IIP Heterogeneous Process for Biodiesel

Esterification &

Transesterfication

Methanol Recovery

Phase Separation

Glycerine Refining

Biodiesel

Purification

Glycerine Phase

Glycerine

Recycle

Methanol

Fresh

Methanol

Fresh

Vegetable Oil

BIODIESEL

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The reaction is performed at highertemperature and pressure than inhomogenous catalyzed processes.

• Excess alcohol is recovered by flashvaporization.

•

Glycerin is separated in a settler andbiodiesel is purified by distillation.

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Chemistry

In the production of biodiesel (methyl or ethyl ester of fatty acids), the

triglycerides of vegetable oils react with alcohol to form ester andglycerin. Fatty acids react with alcohol to form esters and water. Theover all reactions are as follows:

1. Transesterification

R C O CH 2

O

O

CH O C RO

CH 2 O C R

+

+

+

CH 3 OH

CH 3 OH

CH 3 OH

R C O CH 3

O

O

CH O C RO

CH 3 O C R

+ 3

OH CH 2

OH CH

OH CH 2

Triglyceride Methanol Methyester Glycerin

Catalyst, Energy 2. Esterification

Both reactions are equilibrium controlled reactions. R - C - O - H + CH

3 OH R - C - O - CH

3 + H 2 O

Catalyst

Fatty acid Methanol Methyl ester

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Feedstocks

Vegetable oils/ feedstocks having wide range ofFFA or 100% FFA.

Methanol purity is normally at least 99.85 wt%

However lower purity methanol can beprocessed.

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Catalyst

The IIP process uses a unique heterogeneouscatalyst which catalyses transesterification andesterification simultaneously

Provides improved selectivity and unit flexibilityand suppresses corrosion and by productformation.

No pretreatment of vegetable oil is necessary to

remove FFA.

The catalyst also convert FFA into biodiesel.

Catalyst is not deactivated either by water or

FFA.

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Product & byproduct yields

Conversion of triglycerides and FFA is greaterthan 99%.

Yields of ester of over 98% based onTriglycerides and FFA present in the oil areobtained.

Unconverted MeOH is recycled.

Glycerin purity is 99%.

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Main Features of IIP Process

Flexibility for processing variety of vegetable oilsseparately or mixed.

Tolerance of higher levels of free fatty acids.

Requires no pretreatment or removal of FFA. Conversion of free fatty acids present in feed oils

to biodiesel.

Tolerance of water in alcohol and oil The process can produce both methyl and ethyl

esters

Continued...

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No emulsion or soap formation

Biodiesel produced meets the standard

specification (ASTM, European or proposed BIS).

Glycerine produced is ~ 99% pure. Process can be adapted to wide range of

production capacities.

The process is ecofriendly with almost zeroeffluents.

…IIP Process

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Comparison of Biodiesel (IIP Processes) With

National & International Specifications

Characteristics ASTM

D6751

BIS

(India)

Draft EU Jatropha

CurcasOil

Karanja Oil Mahua

Oil

Density, 15°C - 0.86-0.90 0.86-0.90 0.8887 0.8944 0.8808

Viscosity @ 40°C 1.9-6.0 2.5-6.0 3.5-5.0 4.55 5.07 5.13

Flash Point, °C 130 120 >100 135 174 120

Sulfated Ash contentmax., % max

0.05 0.02 0.01 0.008 0.002 0.002

Sulphur max.% mass

0.05 0.05 0.01 <1 ppm 4.5 ppm 4.3 ppm

Cu corrosion 3

hr/50°C, max

No. 4 1 1 1 1 1

Neutral No.mgKOH/g

0.8 0.5 - 0.5 0.6 0.58

Carbon residue %max

0.5 0.05 - 0.13 0.45 0.14

Cetane Number -- 51 -- 56.6 -- --

T h l i l d i

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Technological and economic

benefits

Use of heterogeneous catalyst has directimpact on the economics of biodieselproduction.

Several neutralisation and washing stepsneeded for processes using homogeneouscatalysts such as NaOH, KOH, MeONa etc. areeliminated.

Associated waste streams are eliminated.

E i f Bi di l d ti

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Economics of Biodiesel production:

Effect of Technology improvements -

Process RelativeOperatingcost

Remarks

IIP Process –

I

IIP Process – II

IIP Process –

III

ConventionalProcess

0.93

0.60

0.71

1.0

-Base catalyst, with-Pretreatment step

-Heterogeneous catalyst

-Base catalyst, solventadded to make singlephase

-Base catalyst

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Present Status

Developed and tested solid catalyst for Biodieselproduction batch.

Testing of catalyst in continuous fixed-bed pilot

reactor is being carried out to collect scale updata.

The pilot plant is operating for last 4 months on thesame catalyst charge.

No deterioration of conversion or yield has beenobserved.

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