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8/14/2019 Pre Treatment Technologies 090507
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Cellulosic Biomass Chemical Pretreatment
TechnologiesSeptember 5-6, 2007
Keith Pauley
800-611-2296
Chemical and Environmental
Technologies
Health and Life Sciences Advanced EngineeringSystems
Life-changing Research and Development
www.matricresearch.com
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MATRIC 2
Industrialization of Cellulosic Ethanol
Five factors control the ability for
cellulosic ethanol to becomeeconomically viable: Process rateslow process step
kinetics requires larger capitalequipment costs
Conversion efficiencypoorutilization of feed materials driveshigher operating costs
Capital equipment costsexoticMOC, high pressure or temperaturematerials drive adversely impactcost of goods produced
Operating costshigh temperaturesor pressures require significantamounts of energy
Product quality/consistencyInconsistency increases the cost ofthe overall process
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MATRIC 3
Cellulosic Ethanol Process
Pretreatment phase, tomake the lignocellulosicmaterial such as woodor straw amenable tohydrolysis
Cellulose hydrolysis(cellulolysis), to breakdown the moleculesinto sugars
Separation of the sugarsolution from theresidual materials,
notably ligninMicrobial fermentationof the sugar solution
Distillation to produce99.5% pure alcohol
Chart courtesy of the National Renewable Energy Lab andappears on the Renewable Fuels Association website.
http://www.ethanolrfa.org/http://www.ethanolrfa.org/8/14/2019 Pre Treatment Technologies 090507
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MATRIC 4
Key Processing Cost Elements
www.everythingbiomass.org
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MATRIC 5
Pretreatment Technologies
Mosieret al., Bioresour. Technol. 2005
Pretreatment technologies aremostly used as precursor toenzymatic hydrolysis Acid Hydrolysis
Steam Explosion
Ammonia Fiber Expansion (AFEX)
Alkaline Wet Oxidation
Ozone Pretreatment (Ozonolysis)
Each method has advantages anddisadvantages No one method is best for all types
of feedstock
Optimum reaction parameters of thevarious pretreatments, liketemperature, pressure, and reactiontime, are specific to each feedstock
High yield of sugars does not alwaysresult in high conversion to ethanol lignocellulosic components or
chemicals used in pretreatment mayform compounds that inhibitfermentation
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MATRIC 6
Acid Hydrolysis
Concentrated or dilute mineralacids penetrate biomass,breaking down hemicelluloseinto monomeric sugars, andremoving part of the lignin First cellulosic pretreatment
technology dating from Germanyin 1898
Reaction is carried out atelevated temperatures
Sulfuric acid is most often used,because it is available at low cost
Low moisture content ispreferred, since less energy isneeded to heat the biomass
http://www1.eere.energy.gov/biomas
s/images/photo_05208_sugar_platform.jpg
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MATRIC 7
Acid Hydrolysis
Advantages good hemicellulose sugar
yields
high cellulose digestibility
removal of hemicellulose andlignin exposes more cellulosefor enzymes to attack
can solubilize heavy metals
that may contaminate the
feedstock
Disadvantages requires downstream
neutralization
some degradation of
hemicellulose sugars lower yield of sugars
may form compounds such asacetic acid and furfural which
inhibit bacteria or yeasts
during fermentation
equipment costs are high reactors must be corrosion
resistant, suitable for high
temperature and pressures
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MATRIC 8
Steam Explosion
Physico-chemical pretreatmentin which biomass is subjected to
high-pressure saturated steam,
followed by rapid
depressurization
Expansion of water vapor exertsforce, causing mechanical
breakdown of biomass
degrades hemicellulose and
lignin, thus increasing the
potential of cellulose hydrolysis
acids or bases may be
incorporated into the steam to
increase hydrolysis
www.biogasol.dk/2me2.htm
http://www.biogasol.dk/2me2.htmhttp://www.biogasol.dk/2me2.htm8/14/2019 Pre Treatment Technologies 090507
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MATRIC 9
Steam Explosion
Advantages economical for hardwoods
effectively hydrolyzes
hemicellulose
promotes delignification enlarges pore size in plant
cells which is beneficial for
subsequent cellulose
hydrolysis
Disadvantages increases crystallinity of
amorphous regions of
cellulose, which decreases
cellulose digestibility
high equipment costs
need for high temperatureand high pressure reactors
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MATRIC 10
Ammonia Fiber Expansion (AFEX)
Physico-chemical pretreatment in which prewetted
lignocellulosic material is treated with liquid
anhydrous ammonia at high temperature and
pressure, then pressure is rapidly released
Created and patented by Michigan State University
In contrast to most pretreatments, AFEX does not
significantly solubilize hemicellulose
Pressures exceeding 12 atm are required for operation at
ambient temperature
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MATRIC 11
Ammonia Fiber Expansion (AFEX)
Advantages Much less sugar degradation
than acid pretreatment
inhibitor formation is verylimited
Fast reaction time (~5min)
Improves hydrolysis rates of
hemicellulose and cellulose in
herbaceous crops and grasses
Ammonia can serve as a
nitrogen source for organisms
downstream Ammonia is all volatilized and
can be recovered as gas
neutralization is notnecessary
Disadvantages High energy utilization to
achieve very high pressures
Relatively new and undeveloped
process
Not proven effective onhardwoods or softwoods
AFEX effectiveness decreases
with increasing lignin content
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MATRIC 12
Alkaline Wet Oxidation
Water, sodium carbonate, and oxygen at elevatedtemperature and pressure interact with biomass bybreaking ester bonds Mechanism believed to be saponification of intermolecular
ester bonds that crosslink hemicelluloses with othercomponents
Porosity of the material is increased due to the removal ofthe crosslinks, so enzymes can attack sugars more easily
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MATRIC 13
Alkaline Wet Oxidation
Advantages Readily oxidizes lignin
Significant decrease incellulose crystallinity
more accessible to enzymes
Low formation of furfural, amicrobial inhibitor oftenproduced by other pretreatmentmethods
Disadvantages Degradation of lignin and
hemicellulose to produce
carboxylic acids
hemicellulose sugarslargely decompose, thus
cannot be converted to
ethanol
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MATRIC 14
Ozone Pretreatment (Ozonolysis)
Ozone acts primarily by degrading lignin, via attack and
cleavage of aromatic ring structuresIn one study using wheat straw, ozone pretreatment removed60% of lignin, which increased enzymatic hydrolysis rates five-fold
Sugimoto et al., Ozone Pretreatment for Ethanol Production Using Lignocellulose Materials, Forestry and
Forest Products Research Institute
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MATRIC 15
Ozone Pretreatment (Ozonolysis)
Advantages Effective delignification Ozone does not form any toxic
compounds that inhibithydrolysis
ozone can be easily
decomposed to oxygen usinga catalytic bed or hightemperatures, thus extensivedownstream processing isavoided
Can be conducted at ambienttemperature and pressure
Disadvantages Requires large amounts of
ozone, which is expensive
Generation of carboxylic
acids from extensive lignin
degradation
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MATRIC 16
Summary
None of the current pretreatment technologies
described in this presentation meet the criteria for
economic viability
Each of these technologies is currently being
demonstrated at scale
Further information may change the verdict
MATRIC is currently developing a proprietary
chemical pretreatment technology that has the
potential to satisfy all of the requirements outlinedherein