fuels and chemicals from biomass
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Center for Sustainable Environmental Technologies
Fuels and Chemicals from Biomass
via Thermochemical RoutesRobertC.Brown
CenterforSustainableEnvironmentalTechnologies
Iowa
State
UniversityPresentedat
OpportunitiesandObstaclesinLargeScaleBiomassUtilization
TheRoleoftheChemicalSciences
WorkshopSponsoredby
BoardonChemicalSciencesandTechnology
NationalAcademyofSciences
Washington,DC
May31,2012
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Center for Sustainable Environmental Technologies
UnderstandingFeedstockOptions
Lipidrichbiomass
Lignocellulosicbiomass
Wastebiomass(alloftheaboveplusmore)
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LipidFeedstocks:Almosthydrocarbons
Triglycerides:
threefattyacids
attachedtoglycerol
backbone;found
in
oilseedsand
microalgae
Waxyesters:fattyacidandfatty
alcoholcombination;
foundinjojobaseeds
Isoprene:
buildingblockofterpenes;
naturalhydrocarbonsusually
producedin
small
quantities
in
plantsandmicroorganisms
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4
Lignocellulose:NaturallyRecalcitrant
A three-dimensional polymeric
composite that resists biological
degradation Polymeric constituents:
Cellulose: main source of glucose
(C6 sugar) Hemicellulose: source of xylose
(C5 sugar)
Lignin: polymer of monolignols
Glycosidic
bonds
Cellulose
Lignocellulose
p-coumaryl
alcohol
coniferyl
alcohol
sinapylalcohol
Monolignols of lignin
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LipidsvsLignocellulose
Source:NatureMedicine
11,599 600,2005.
CO2H2O
Plant No. 1
Plant No. 2
Lipidbiosynthesis
involvesbiological
deoxygenationof
carbohydrates,too!
Cellulosetohydrocarbons
involvesdeoxygenation
of
carbohydrate
Lipid
CO2
CO2
Which Kind of Plant Should be Used to Deoxygenate Carbohydrate?
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GeneralizedThermochemicalProcess
Upgrading
Depolymerization/Decomposition
Feedstock
Thermolytic
Substrate
Biofuel
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Gasification
Low Temperature Gasification
(Bubbling Fluidized Bed)
High Temperature Gasification
(Entrained Flow Gasifier)
Thermaldecompositionoforganicmatterintoflammablegases
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Syngas
Gasificationcanbeapproximatedasanequilibriumreaction
Compositionofsyngas (volumepercent)
Hydrogen Carbon
Monoxide
Carbon
Dioxide
Methane Nitrogen HHV
(MJ/m3)
32 48 15 2 3 10.4
Inpractice,equilibriumnotattainedandtarandchararepresent
Syngasalso
contains
small
amounts
of
alkali
metals,
sulfur,
nitrogen,andchlorinethatmustberemovedbeforeupgradingtopreventpoisoningofcatalysts.
Biomass
Particulat
eRemoval
Tar
RemovalSulfur
RemovalAlkali
Removal
Catalytic
Synthesis
Gasifier
Biofuel
RawSyngas
Oxygen/Stea
m
Nitrogen
Removal
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GasificationStrengths
Technical Consumesallofthefeedstock
(carbohydrateand
lignin)
Producesuniformintermediateproduct(syngas)
Multipleapplications:heat,power,
fuels,
chemicals
Commercial
Notfinickyaboutfeedstock
Proventechnologyforcrackingthelignocellulosicnut
Allowsenergyintegrationin
biorefineryoperations tpd gasification plant at ISUsBioCentury Research Farm
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Center for Sustainable Environmental Technologies
GasificationChallenges
Technical Gascleaningtechnologiesstill
underdevelopment
Gasificationandfuelsynthesisoperationsmustbecloselycoupled
Fuel
synthesis
occurs
at
high
pressuresand
exacting
stoichiometries
Commercial Demandslargescaleoperations
Highcapitalcosts
Mustcompletewithsteam
reformingof
natural
gas
Pressurized, oxygen-blown
entrained flow gasifier at ISUsBiorenewables Laboratory
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FastPyrolysis
Gas noncondensablegaseslikecarbondioxide,carbon
monoxide,hydrogen
Solid mixtureofinorganiccompounds(ash)andcarbonaceous
material(char)
Liquid mixtureofwater
and
organic
compounds
knownasbiooilrecovered
frompyrolysisvaporsand
aerosols(smoke)
Bio-oil
Thermaldecompositionoforganicmatterintheabsence
ofoxygentoproduce:
Biochar
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Technology Residence
Time
HeatingRate Temperature
(C)
Predominate
Products
carbonization days verylow 400 charcoal
conventional 530min low 600 oil,gas,char
gasification 0.55 min moderate >700 gas
fastpyrolysis 0.55s very high 650 oil
flashliquid
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Center for Sustainable Environmental TechnologiesFastPyrolysis
Rapid thermal
decomposition to produce
predominately liquid
Dryfeedstock:
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PyrolysisChemistryisPoorlyUnderstood
Depolymerizationvs.
alkali
catalyzed
decomposition
of
cellulose
Vaporizationvs.repolymerizationoflevoglucosan (LG)tooligomers
Dehydrationofoligomerstolightoxygenatesorchar
Research at ISU indicates several stages of
competitive processes during cellulose pyrolysis:*
Note: LMW (low molecular weight products) include H2O, CO2, 5-HMF, furfural, furan, carboxylic acid, etc.
Cellulose
Alkali-catalyzed decomposition
LG vapors
LMW products
polymerization
Depolymerization
evaporation
LG oligomers
LMW products
LG polymer
LMW
products+ char
LiquidLG
*Hemicellulose and lignin similarly go through several stages of depolymerization or dehydration
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FastPyrolysisStrengths
Technical
Rapid(afewseconds)
Atmosphericoperation
Pathwaytodropinfuels
Multipleproducts
Newtechnologiesemerging
(catalyticpyrolysis)
Commercial Lowestcostoptionfordropinbiofuelsatpresent
Pyrolyzersassmallas200tpd
Opportunitiesfor
distributed
processing
tonperdayfastpyrolysispilotplantat
ISUBioCenturyResearchFarm
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FastPyrolysisChallenges
Technical
Biooil
has
high
oxygen
and
watercontent
Biooilunstableandcorrosivein
storage
and
upgradingFundamentalsofpyrolysis
poorlyunderstood
Commercial Nodemonstrationsofbiooilproductionandupgrading
Pathwaytofinishedfuelsstilluncertain
Freefallpyrolyzerforfundamental
studiesunderconstructionatISUs
BiorenewablesResearch
Laboratory
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CatalyticPyrolysis
Definition:Catalystsemployedinthepyrolysisreactor
orimmediatelydownstreambeforebiooilrecovery
Twomajor
approaches:
Catalyticcracking(doesnotrequirehydrogen)
Hydropyrolysis
(carbon
efficient) Advantage:Produceshighlyreducedmolecules
Challenge:Yieldsarerelativelylowduetocoking
Commercialization:Large
number
of
companies
are
exploringthisapproachalthoughfundamental
chemistryisnotwellunderstood
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Solvolysis
Definition:Pyrolysisinasolvent
Twomajormanifestations:
Directliquefaction(DL)toproducepartiallydeoxygenatedbiocrude
Hydrothermalprocessing(HTP)tosugarsandlignin
Advantagesandchallengesaresimilartofast
pyrolysiswithaddedchallengeofoperatingathigh
pressures Commercializationexamples:
DL:Catchlight(ChevronWeyerhauserjointventure)
HTP:Renmatix
(Kleiner
Perkins
backed
start
up)
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UpgradingThermolyticSubstrates
Syngas:Mixtureofcarbonmonoxide(CO)andhydrogen(H2)derivedfromgasificationoforganicmaterials
BioOil:Highlyoxygenatedorganiccompoundsderivedfromfromfastpyrolysis
BioCrude:Partiallydeoxygenatedorganiccompoundsderived
from
direct
liquefaction
or
catalytic
pyrolysis
of
biomass.
Solubilizedcarbohydrate:Aqueoussolutionofmonosaccharides,
anhydrosugars,
and
other
water
soluble
compoundsderivedfromplantcarbohydratesusingavarietyofprocessesincludingacidorenzymatichydrolysis,fastpyrolysis,andhydrothermalprocessing
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Deoxygenation
Idealization:C6H12O6+H2 C6H14+3O2
Inpractice,oxygenremovedasCO2orH2O
Examples:
Ethanolfermentation(biocatalyticupgrading)
C6H12O62C2H5OH+2CO2
Gasification/FischerTropsch
Synthesis
C6H12O6+3H2O6H2+3CO+3CO2
(2n+1)H2+nCOCnH2n+2+nH2O
Animportantpartofallbiomassupgrading
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SyngasUpgradingtoFuels
Catalytic performedatmoderatetemperaturesandhighpressures
usingmetal
catalysts
FischerTropschsynthesistohydrocarbonssuitableforfuels
Methanol
synthesis
followed
by
upgradingtogasoline
Ethanolsynthesis
Syngasfermentation
performed
atambienttemperatureandpressureusingbiocatalysts
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UpgradingBioOil:WhatsinIt?
Lightoxygenates(ringbreaking):carboxylicacids,aldehydes,
ketones,alcohols.
Furans(products
of
carbohydrate
dehydration)
Sugars(depolymerization):Monosaccharides,anhydrosugars,
oligosaccharides.
Levoglucosan
O CHOHOH2C
5-hydroxymethyl furfural
CarbohydrateDerivedCompounds
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Repolymerizedmonomers:
Phenolicoligomers
Consistingofasmanyas50to80monomericunits
To
produce
diesel
fuel
(C10
C24),
thephenolicoligomersshould
occurasdimers(C14)ortrimers
(C21)of
2methoxy
phenol 0
0.2
0.4
0.6
0.8
1
1.2
10 100 1000 10000
Area
MolecularWeight(Da)
MolecularWeightDistributionof
WaterInsolubleFraction
Depolymerizationoflignin:
Substitutedphenolic
monomers
UpgradingBiooil:WhatsinIt?Lignin
Derived
Compounds
2-methoxy phenol
phenolic oligomers
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UpgradingBioOilViaPetroleumRefiningTechnology
Hydrotreating (removalofheteroatoms) Deoxygenation,desulfurization,denitrification,and
demetalization Cracking
Reductioninsizeoflargemoleculestofuelrange
Condensation Reactionoftwomoleculestoproducealarger(fuelrange)
moleculeandasmallmolecule
Oligomerization Reactionofmonomerwithanothermonomer,dimer,etc.
toproducelargermolecules(oligomers)
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RenewableCrude:SolubilizedCarbohydrate
Sugarscanbecatalyticallyconvertedto
hydrocarbonsviaaqueousphase
processingif
cheap
feedstock
available
Commerciallyavailablefeedstocks:Sugar
caneandcornstarch
Constrainedbycostandfoodvs.fuel
concerns
Promisingfeedstock:Lignocellulose
Requiresdeconstructiontosugarmonomers
Canbeaccomplishedviaacidhydrolysis,
enzymatichydrolysis,orthermal
depolymerization
Pyrolytic dextrin
(>20wt%
sugars)
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ThermalDepolymerizationtoMonomers
Secureasource
of
clean
straw
(orotherlignocellulose)
Infusebiomasswitha
diluteacidsolution Bakeitinahotoven
(set
the
timer
for
2
seconds)
Washoutthesugars
Gasolineorethanol
Bioasphalt,chemicals,fuels
Sugar
Phenolics
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FutureInnovations?
GasificationChallenge Innovation
Transport,storage, andpressurized
feedingofbiomass
Preprocessingofbiomassintotorrefied biocoal,
pelletizedfeedstock,orbiooil
Demanding operatingconditions
forcatalyticsynthesistofuel
Substitute biocatalyst(syngas
fermentation)
Highcapitalcosts Operationatatmosphericpressureandwith
fewerunitoperationsforgascleaning
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FastPyrolysisChallenge Innovation
Complexchemicalcompositionof
biooilmakes upgradingdifficult
Recoverbiooilasfractionswithsimilarphysical
andchemicalproperties
Biooilishighlyoxygenated Catalyticpyrolysisforinsitudeoxygenationof
pyrolysis products
Goldilocks dilema:Moleculesare
eithertobigortoosmallforideal
upgrading
Thermaldepolymerizationto monomers
(monosaccharidesandphenolicmonomers)
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AdditionalInformation
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