“Products and Energy from Renewable Resources”
PSE 104
Summer 2009
Agenda
Course outline Biofules, Biochemicals and
Bioenergy Biomass chemistry
Your co-instructor: Renata Bura
B.Sc.,1997, Ryerson University, Toronto, Canada, Chemistry
M.A.Sc., 2000, University of Toronto, Chemical Engineering and Applied Science and Environmental Engineering
Ph.D., 2004, University of British Columbia, Vancouver, Canada, Forestry
Post Doc., 2006, UBC, Vancouver, Canada
2006, joined UW-Assistant Professor in Natural Products Chemistry
What can you expect from me?
Starting and finishing lectures on time Responding to your e-mails (up to 2
days) Being in my office during office hours Teaching the best to my ability There are no “stupid questions”
Rules in the classroom
Cellphones Laptops Rules of discussion
(1) Biofuels and biochemicals
ConversionBiofuels
BiochemicalsBiomass
(2) Energy from renewable resources
Energy
Bioenergy, biofuels, biomass
Bioenergy: energy derived from wood, straw or waste
Biofules: fuels produced from biomass (bioethanol, biodiesel, biobutanol)
Biomass: all the earth’s living matter is biomass» Can be burned to produce heat and power» Can be converted to biofuels
Lignocellulosic biomass: biomass composed of cellulose, lignin and other chemicals
Biomass
Energy crops» Wood crops » Agricultural corps
Wastes» Wood residues» Temperature crop wastes
– Wheat straw, rice straw
» Tropical crop waste– Rice husks– Sugar cane baggase
» Municipal solid waste
Dedicated energy crop
Dedicated energy crop: plants grown specifically for applications other that food or feed.
» Planted and harvest periodically – Annual basis (sugar cane)– 3-10 year cycle (hybrid poplar)
Dedicated energy crops contain significant quantities of one or more of 4 energy rich components
» Oils» Sugars» Starches» Lignocellulose
Herbaceous energy crops (HEC) (annuals and perennials)» Sugar cane, energy cane, napiergrass, sorghum » Short-rotation wood crops (SRWC)» Willow, oak, poplar, maple, eucalyptus
Napiergrass
Sorghum
What is Bioconversion?
General: a process which uses biological agents (microorganisms or protein) to transform a feedstock into desirable products.
Bioethanol A chemical/biochemical process by which
lignocellulosic materials are converted to ethanol and other co-products.
Why Bioconversion?
Energy» An alternative source of energy for the
transportation sector produced locally Air pollution
» Reduction in greenhouse gas emissions Waste elimination
» Elimination of problems with field burning/incineration, stockpiling, etc.
Socio/economical benefits» Creation of new jobs, rural development
Fundamentals of biomass chemistry
Cellulose Hemicellulose Lignin
Bioethanol from Sugar Cane
Energy balance History Problems Production
Bioethanol from Corn
Corn to ethanol» Energy balance» Problems» Production
– Dry milling– Wet milling
Bioethanol from Lignocellulosic Biomass
Feedstock diversity» Pretreatment » Hydrolysis» Fermentation
Biodiesel
Why biodiesel? How to make it?
» Possible sources Biodiesel and cars
How is Biomass like a Kellogs™ Rice Krispies Treat?
Your warped instructor needed some sort of an analogy to assist people in understanding biomass.
This is it.
Image borrowed from Kellogs™ web site for academic purposes
Rice Krispies Alone
At my home, a box of Rice Krispies consists of 2 things: Rice Krispies and Rice Krispies dust.
You can pour this mixture into a bowl but you cannot stand it up or make a bar.
Image borrowed from Kellogs™ web site for academic purposes
Formation of the Bar
You also need something to preserve the bars….A variety of preservatives can be used.
In order to make a solid bar, you need something to glue together the Rice Krispies and the Rice Krispies dust.
Marshmallow cooked over an open flame works great.
Rice Krispies Treats
Ingredient Amount Wood Equivalent
Big Rice Krispies 1 3/4 cups Cellulose
Rice Krispies Dust 1 cup Hemicelluloses
Marshmallow 1 1/8 cup Lignin
Butter 3 tablespoons Lignin
Preservatives ~ 1-5 tablespoons Extractives
The butter and the marshmallows are heated together forming a sticky glue type material.This is applied to the Rice Krispies and dust forming a bar which is solid when cooled.
What is Cellulose?
Cellulose is a large molecule made from glucose molecules (dextrose) strung together like beads on a string.
The glucose molecules are known as monomers and the cellulose chain is known as a polymer. » 1 glucose molecule= monomer » 2 linked glucose molecules= dimer» 3 linked glucose molecules= trimer» lots of linked glucose molecules = polymer
What is Cellulose?
Cellulose is straight chain polymer. In bead terms, imagine a very very long straight string of beads with 2 ends and no branching points.
In wood, cellulose chains contain typically 10,000 glucose molecules…quite a long sting of beads.
Source: World Book Encycopedia
Cellulose Very long straight chain polymer of glucose (a sugar): approximately 10,000 in a row in
wood. Cotton is nearly pure cellulose.» Think about a very long string of beads with each bead being a glucose molecule.
Cellulose molecules link up in bundles and bundles of bundles and bundles of bundles of bundles to make fibers.
Uncolored polymer.
O
O O
O
O
O
O
O
CH2OH
OHHO
OHHO
CH2OHOH
CH2OH
HO
OH
CH2OH
HO
O
Cellulose
Cellobiose Unit
What are Hemicelluloses?
Hemicelluloses are also sugar polymers but different from cellulose because they are:» Made up glucose and other sugars.» Contain some molecules other than sugars.» Branched little polymers
– Much smaller than cellulose as they are made up of between 50-300 sugars (Rice Krispies Dust)
There are lots of varieties of hemicelluloses.
Hemicelluloses
Branched little uncolored sugar polymers (~ 50 to 300 sugar units)» Composition varies between wood species.
– 5 carbon sugars: xylose, arabinose.– 6 carbon sugars: mannose, galactose, glucose.– Uronic Acids: galacturonic acid, glucuronic acid.– Acetyl and methoxyl groups (acetic acid &
methanol). Major hemicelluloses:
» Xylans - big in hardwoods» Glucomannans: big in softwoods
Minor hemicelluloses: pectins, others.
Xylan Structure
4--D-Xly-14--D-Xly-14--D-Xly-14--D-Xly4--D-Xly
4-O-Me--D-Glc
-L-Araf
O O
O
O
O
O
OH
OHHO
HO
HO OH
OO
O
HO OH
O
O
CO2HH3CO
OHHOH2C
O
O
OH
Glucomannan Structure
4--D-Glc-14--D-Man-14--D-Man-14--D-Man-1
2,3
Acetyl
6
-D-Gal1
There are different structured glucomannans in hardwoods and softwoods (and within softwoods)
Glucomannans are mostly straight chained polymers with a slight amount of branching. The higher the branching, the higher the water solubility.
What is Lignin?
Lignin is a polymer like cellulose and hemicelluloses but is made with phenolic compounds (aromatic rings) instead of sugars.
Lignins are large 3 dimensional polymers that form the glue that holds the cellulose and hemicelluloses together.
Lignin has been described as 3 dimensional chicken wire.
Picture taken from Katy’s chicken page.
Lignin
Phenolic polymer - the glue that holds the fibers together.
Lignin is a very complex polymer which is connected through a variety of different types of linkages.
Colored material.CH2 O
OH
OCH3
COHH
HC
CH2OH
OH CH2OHC
O
H3CO
C O
CH
CH
H
CH
CHOH2
HO
H
CH
OCH3
OH
C
OH2C
CHO
O
C
CH2OHH3C
O
O
COH
O CH
H3C
CH2OH
H
HCOH
1
2
3
4
5
6
7
H
HC CH
O
O CH
CH2O
C
OCH3
O
CHO
H2C
H3C
8
OHC CH CH2OH
CH2OH
O
O
C
OH
H3C9
10
O
HC CH
COHH2
CH2O
CH
O
OH
H3C
11
H3C
12
HO
CH2OHH3C
13
O
C
O
CH
O CH
O
H3C
H
CH3
CH
OH
O
CH
H3C
CH
H2COH
15
16
Carbohydrate
CH2OH
OH
OCH3
HC 14
H2COH
HC
CHO
17
HOCHO
O
C O CH2
H3C18
HCHO
O
H
H3C
19
O
CH
OCH
O
CH
O
COHH2
OH
OCH3
COHHCOHH2
20
H
CH
H2COH
OCH3
O
HC O
C
OCH3
CH
CH
CHO
22
21
O
H2COHCH2
CH2
H
C O
C
OCH3
24
25
26CH
28
27
O
CH2OH
H
CH3
CH
O
O
H2COH
H
H2COH
H3C
H3C
H2COH
O
CH
CH
OHC
O
O
O
H
23
COH
OCH3
What are Extractives?
In the Rice Krispies model, extractives compounds were represented by preservatives added to the treats. This is a very good representation of the role of a good portion of the extractives in trees.
The term extractives refers to a large variety of different chemicals produced by the tree for a variety of reasons (protection, food storage, formation of membranes, color, etc.).
Examples: what sticks to your hand when you pick up your Christmas tree, what comes out of your tea bag with hot water.
Extractives
The term extractives refers to a group of unique chemical compounds which can be removed from plant materials through extraction with various solvents.
Typically these chemicals constitute only a small portion of the tree (<5%).» In some tropical species this can be as high as
25%. Extractives are produced by plants for a variety of uses.
» The most common use by plants is protection. Extractives can cause serious problems for processing. Pitch is a term which is often used when describing some
groups of extractives. Extractives are responsible for the characteristic color and
odor of wood.
Putting it All Together
Putting all of the components together and you get biomass. The cellulose and the hemicelluloses held together with lignin.
Taking the lignin away through chemical processes (pulping and bleaching) leaves these fibers of cellulose and hemicelluloses.
Picture from Focus Forest Products Web Site
What is the chemical makeup of wood?
0
10
20
30
40
50
60
%
Douglas Fir Redwood Yellow Pine Balsam Fir
Cellulose*Hemicellulose*Lignin*Extractives
* Data for Cellulose, Hemicellulose & Lignin on extractive free wood basis
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