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Dr Zhe Li
Senior Lecturer in Materials Science
Renewable Energy MaterialsQXU7027
A world of possibilities…
Palm oil waste
15.8 Mt/yUnripe coconut
husks 5 Mt/yCassava starch
228 Mt/y
1 Mt/y of
food wasteAgro-residues
46 Mt/y
Spent coffee
grounds 3 Mt/y
Orange peels
12 Mt/y30 Mt/y of Agro-
residues 382 t/y
coffee husks
Waste is tomorrows resource
We need to encourage the greater use of chemically rich waste as a resource
Sugars
Phenols
Natural Dyes
Chitosan
Chitin
Starch
Alginic Acid
Lipids
Pectin Proteins
HemicelluloseCellulose
Lignin Waxes Tannin
What´s in biowaste?
Lignocellulosic Biomass (Agricultural wastes) as an example…
1. Most abundant renewable biomass resource on the planet ( 1.9 trillion tons/year)
2. We can not eat it…so no competition between fuels and food
Cellulose (纤维素)Lignin (木质素)
50‐70% 10‐40%10‐30%
Hemicellulose(半纤维素)
How we can separate cellulose and hemicellulose from lignin?
• 3D amorphous polymer
• cross-linked phenolic polymers
• Forms cell walls of woods and bark
• an organic compound with the formula (C6H10O5)n
• primary cell wall of green plants
• Both crystalline and amorphous parts
• Random, amorphous structure with little strength.
• often coexisits with cellulose but with very different structure
Cellulose (%) Hemicellulose (%) Lignin (%)
Hardwood stems 40–55 20–40 18–25
Softwood stems 45–50 25–35 25–35
Rice straw 35–45 18–25 10–25
Wheat straw 38–45 20–32 7–10
Tobacco chops 22–30 15–20 15–25
Arundo donax 30–38 18–22 8–20
Miscanthus 35–40 16–20 20–25
Newspaper 40–55 25–40 15–30
Composition of some common used lignocellulosic biomasses
➢ Can not hydrolyse cellulose to glucose(葡萄糖) because of the high degree of crystalinity
➢ Cellulose, hemicellulose and lignin are naturally packed and protected against chemical breakdown
➢ Neither cellulose and lignin are soluble in any conventional solvents
How we can separate cellulose and hemicellulose from lignin?
Challenges:
Separation Method 1: Kraft Process
• A process for conversion of wood into wood pulp, which consists of almost pure cellulose fibres, the main component for e.g. paper and other chemicals.
• The kraft process entails treatment of wood chips with a hot mixture of water, sodium hydroxide (NaOH), and sodium sulfide (Na2S), known as white liquor, that breaks the bonds that link lignin, hemicellulose, and cellulose.
• Controversial as Kraft plants can release odorous products and in some situations produce substantial liquid wastes.
Separation Method 2: Organosolvation
• Organosolv is a very promising approach
• Organic or aqueous organic solvent mixture with inorganic acid catalysts (HCl or H2SO4) is used to break the internal lignin and hemicellulose bonds.
• The solvents more frequently used in organosolv processes are acetone, methanol, ethanol, phenols, ethylene glycol and tetrahydrofurfuryl alcohol.
• After precipitation, the recovered lignin (organosolv lignin) is a is a sulfur‐ free lignin, with high purity and low molecular weight, to be used for many purposes.
Separation Method 3: Ionic Liquids (ILs)
ILs are salts generally formed by large organic cations and small inorganic anions, which are liquid at low temperature and can be used as non–aqueous alternatives to traditional organic solvents.
Advantages
●tunable properties (e.g., viscosity, melting point, polarity, and hydrogen bond basicity) depending on the selection of the anion and cathion.● high chemical and thermal stability● non–flammability● low vapour pressures (they remain liquid in a wide range of T)●good (selective) solvation properties due to the swelling of the plant cell wall, with disruption of inter– and intra–molecular hydrogen bonding between lignin and cellulose, and also to the possible electronic interaction of the organic cathions and the aromatic rings of lignin
Drawbacks
● high viscosity (a serious limit to mass and phase transfer)
● Expensive and only Kg scale production
Separation Method 3: Ionic Liquids (ILs)
Petroleum
feedstock
Fuels
Solvent
Bulk chemicals
Plastics
Fibres
Fine chemicals
Oils
Petroleum Refinery
Bulk chemicals
Solvent
Plastics
Fine chemicals
Fibres
Oils
Biowaste
An analogous to Petroleum Refinery-Biorefinery
Fuels
What can we do with biomass?
Biofuels
• Bioethanol• Biodiesel• Hydrogen• Methane• Hydrocarbons
Chemicals
• Glycerol• Acids• Aldehydes• Furanes• Heterocycles
Materials
• Carbon• Polymers• Carbon Fibrers• Composites• Inorganics
What can we do with biomass?
Biofuels
• Bioethanol• Biodiesel• Hydrogen• Methane• Hydrocarbons
Chemicals
• Glycerol• Acids• Aldehydes• Furanes• Heterocycles
Materials
• Carbon• Polymers• Carbon Fibrers• Composites• Inorganics
• “Proalcool “program: Brazil’s National Fuel Alcohol Program promoted by the oil crisis in the ´70s
• SUGARCANE TO ETHANOL
• USA followed in the 90s with a massive production of ethanol (CORN TOETHANOL)
• EU is moving towards a mandatory biofuel usage of 10% of the energy used by 2020
• Japan has set a goal of replacing 20% of its oil demand with biofuels or gas to liquid fuels by 2030
Bioethanol
• Sugar Cane• Sugar Beet• Sweet Sorghum
ADVANTAGES
• High yield of sugar/acre• Low conversion costs• Ethanol from sugarcane in Brazil
costs 0.81$/gallon
DISADVANTAGES
• Natural seasonal and local availability• Compete with food
Bioethanol from Sugar
• 10% of the cultivated land (13.8 million acres)
• Over 50% of Brazil’s sugar cane production for ethanol production
• The leftovers (leaves, fibers‐called BAGASSE) isused to generate steam and then electricity forthe biorefinery
• The liquid effluent (waste-water vinasse) isused as fertilizer and irrigation supply of thecane fields
• Brazil´s ethanol is the cheapest in the world
• Today the effort are directed towards expanding sugar cane refineries through the processing of bagasse for cellulosic ethanol
• This will improve the economics and allow ethanol production during winter
Sugarcane in Brazil
• Major source of sugar in Europe and North America• Used for Bioethanol production in France• Can generate 20‐50 tones of sugar beet per acre• Ethanol yield is 25 gallons/ tone of sugar beet• Requires a greater energy input and therefore is more expensive
Sugar Beet
1gallon= 4.5L
Sweet Sorghum
• Not widely grown
• The sugar is contained in the main stalk
• Sugar is recovered by pressing the stalks with rollers
• Yields are around 20 gallons ethanol / t of stalks
• China wants to switch from corn to sweetsorghum for the regions where corn doesnot grow well
• The best economical option would be to engineer a station where one could switch between ethanol as a fuel and sugar production
Sugar Cane BiorefinerySugarcane
Sugarcane crush rollers
First lime addition and filtration
Juice heating
Sugar crystal centrifugation
Syrup A Molasses
2‐nd lime addition and filtration
Sugar Crystal Centrifugation
Syrup B Molasses
Enzymatic Saccharification
Yeast Fermentation
Distillation
SUGARCANE SUGAR BEETS SWEET SORGHUM
LIME Ca(OH)2
LIME
SUGAR
B MOLASSES
CONDENSED MOLASSESSOLUBLES FOR ANIMALFEED
HYDROUS ETHANOL
INVERTASE, DEXTRANASE
SACCHAROMYCES CEREVISIAE
• Corn is the second largest feedstock source for ethanol production worldwide
• Most important starch feedstock
• 11 billion gallons of ethanol were produced from 2 bilion tones of starch worldwide
• Ethanol production from corn is concentrated inUS
• Spain, Germany, France and UK uses wheat to produce ethanol
• Rye and barley are also used in Spain and Germany
• Corn has a longer lifespan than sugar crops
• The use of corn adds another step to ethanolproduction as starch must be first broken into itsconstituents sugars
ETHANOL FROM STARCH
ETHANOL FROM STARCH
Dry Mill/Grind
Corn Milling
Liquefaction
Cooking
Yeast Fermentation
Beer Well
Distillation
Drum Dryer
CORN
CARBON DIOXIDE
DRY DISTILERS GRAIN SOLUBLES
AMYLASE/GLUCOAMYLASE
SACCHAROMYCES CEREVISIAE
Food Grade Ground Corn
Enzymatic Saccharification
HYDROUS ETHANOL
Dehydration
Centrifugation
ETHANOL
Wet Distillers Grain
Wet Cake Processing
Thin Stillage Processing
Dehydration Evaporation
ADVANTAGES:➢ No competition with food➢ 50‐80% estimated reduction in the emissions compared with gasoline
DISADVANTAGES:➢ Needs additional substances and processes to break down plant fibbers into fermentable
sugars➢ Not the same bacteria that convert glucose ( 6C) can also convert pentose ( 5C)➢ Costs are high
ETHANOL FROM LIGNOCELLULOSIC BIOMASS
ETHANOL FROM LIGNOCELLULOSIC BIOMASS
Lignocellulose
Biomass Densifying Chopping
Fine Grinding
Heated Biomass Hydrolysate Production
Neutralization
Cellulose Hemicellulose Enzymatic Treatment
Lignin Separation
Liquid Hydrolysate
Enzymatic Scarification
Yeast Fermentation
Distillation
SWITCHGRASS SWITCHGRASS ENZYMES OIL PLANTS WITH LIGNOCELLULOSE
Cellobiase, dextrinase, amylase, pectinase, exoglucanase, peroxidase, xylanase, etc
Saccharomyces Cerevisiae
Lignin
Ethanol
Plant Oil Removal
• 94% less carcinogenic particle matter• Lower sulfur content• Less volatile• Easier to handle• Degrades more rapidly‐lower environmental impact
BIODISEL is the most widely used biofuel in Europe
Fatty acid alkyl esters
Others:• Palm oil• Soybeans
BIODIESEL FROM VEGETABLE OIL
Rudolf Diesel, 1912
“…the fact that fat oils from vegetable sources can be uses as many seem insignificant today,but such oils may perhaps become in course of time of the same importance as some naturalmineral oils and the tar products are now”
• from the 70‐90´s there were many problems using vegetable fats directly in Diesel engines because of the high viscosity
• emulsions with diesel oil, vegetable oil and water were similar to the original fuels, however with lower NOx emissions than original diesel oil or original vegetable fasts.
• emulsions have never been implemented because of fear of phase separations as well as water corroding the engine
BIODIESEL FROM VEGETABLE OIL
• All the problems with deposits in the engine due to the high viscosity of pure vegetable fats was solved by converting the triglycerides (甘油三酯) in the oil to alkyl esters
• These alkyl esters become known as biodiesel
• This was first demonstrated by Knothe in Belgium
• Several Biodiesel plants were buit in Europe in the late 80´s
• US formed the “ National Soydiesel Development Board” in 1992
BIODIESEL FROM VEGETABLE OIL
BIODIESEL PRODUCTIONTRANSESTERIFICATION
• Reacting the feedstock with an alcohol in the presence of a catalyst
A COMPLETE BIODIESEL PLANT
Reactor
OIL
Methanol
Catalyst
SeparatorMethyl Esters Neutralization
and methanolremoval
Water washing
DryerBIODIESEL
Gray water
Water
Acid
Methanol/water rectification
Wet methanol
WaterMethanol Storage
Glycerin (50%)
Acidulation and separation
Methanol Removal
Acid
Free fatty acids
Crude glycerin (85%)