Fuels and Chemicals From Biomass

8/12/2019 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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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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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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