Enhanced Biomass Hydrolysis with Enhanced Biomass Hydrolysis with Hot Wash SeparationHot Wash Separation

Melvin P. Tucker, Nick J. Nagle, Edward W. Jennings,Melvin P. Tucker, Nick J. Nagle, Edward W. Jennings,John John JechuraJechura, and Richard T. , and Richard T. ElanderElander

National Renewable Energy LaboratoryNational Renewable Energy LaboratoryNational National BioenergyBioenergy CenterCenter

Golden, COGolden, CO2003 AIChE Annual Meeting

Separation of Processing Streams Derived from Renewable Feedstocks (Session 162)

San Francisco, CANovember 20, 2003

Operated for the U.S. Department of Energy by Midwest Research Institute • Battelle

OutlineOutline

BackgroundReactors and filterIntegrated pretreatment and “hot-washing” of yellow poplar sawdust and corn stoverDigestibility of residual celluloseConclusions

BackgroundBackground

• Lignin affects the enzymatic hydrolysis of pretreated biomass.

• Small amount of lignin is solubilized by dilute acid and steam pretreatments.

• Lignin may re-precipitate upon pretreated solids when cooled.

• Bench scale experiments show solubilizedlignin can be removed by a flowing liquid medium at elevated temperatures.

• Enhanced enzymatic hydrolysis of residual cellulose to glucose.

BackgroundBackground

• Present pretreatment process is a dilute –acid prehydrolysis step followed by enzymatic hydrolysis of the residual cellulose to glucose.

• One possible improvement to this process is the inclusion of a “hot wash” step following the dilute-acid prehydrolysis.

• “Hot wash” concept developed at NREL (U.S. Pat. No. 6,228,177).

BackgroundBackground

Related WorkUniv. Hawaii (Antal et al.)– Liquid hot water/steam in an

immersion/percolation reactorBatch steam and LHW immersionLHW with intermittent addition and removal

– Enhanced xylan solubilization, xylose recovery (oligomers), lignin solubilization, and enzymatic digestibility, especially at higher L:S ratios (>10:1)

BackgroundBackgroundRelated Work

Dartmouth College—CAFI (Wyman et al.)– Liquid hot water and dilute to very dilute

sulfuric acid– Batch, flowthrough, and start-stop flow

regimes– Relates xylan removal, xylose recovery,

monomer:oligomer ratio, lignin removal to flow regime

Function of flow rate, flow velocity, L:S, acid conc., etc.

BackgroundBackgroundThis work

Outgrowth of flowthrough percolation “wonderwood” process– Greater xylan and lignin removal, higher xylose

yields, resulting in enhanced enzymatic digestibility

Technoeconomic analysis identified that high L:S ratio is a “show stopper”– Dilution effects– Steam demands to heat up required liquid

volumes in pretreatment

This WorkThis Work

Decouple the pretreatment and separation/washing– High solids pretreatment (>25% solids)– “Hot” separation and washing

Temppretreat > Temps/w > Templignin phase trans.

– Validated in bench-scale device– Scaled to a pilot-scale system

BenchBench--Scale Scale ““Hot WashHot Wash”” Test System Test System

Stirred Parr ReactorStirred Parr Reactor(1 L)(1 L)----inside inside heating mantleheating mantle

Preheated Wash Preheated Wash Liquor AdditionLiquor Addition

Pneumapress Pneumapress Filter Test UnitFilter Test Unit----inserted in inserted in heated sand bath heated sand bath during operationduring operation

Heated Sand Heated Sand BathBath

Piping and Valve Piping and Valve for Elevated for Elevated Temperature Temperature Transfer from Transfer from Parr Reactor to Parr Reactor to Pneumapress Pneumapress Filter Test Unit Filter Test Unit

Hot Wash Process ConfigurationHot Wash Process Configuration

• Separation/washing can occur at lower temperature than pretreatment reaction• ~160-200°C for pretreatment reaction• ~130-140°C for separation/washing

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N o S e p arat io n o r Wa s hingHo t S e p arat io n OnlyHo t S e p arat io n a nd Wa s hing - - 10 :1 L:S R at io

Enzymatic Digestibility of Hot Washed Pretreated Enzymatic Digestibility of Hot Washed Pretreated Biomass from Bench Scale EquipmentBiomass from Bench Scale Equipment

Hardwood (Yellow Poplar)

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No Separation or Washing

Hot Separation O nly

Hot Separation and Washing--12.5:1 L:S Ratio

Enzymatic Digestibility of Hot Washed Pretreated Enzymatic Digestibility of Hot Washed Pretreated Biomass from Bench Scale SystemBiomass from Bench Scale System

Corn Stover

Pilot Scale Pilot Scale ““Hot WashHot Wash”” SystemSystem

Feed Hopper

Plug Screw Feeders

Horizontal Reactor

Plug Screw Feeder

Discharger

Discharge Valves

Pneumapress Filter

Pressurized Solids Tank (Jaygo Reactor)

Steam, Hot Water, Hot Acid or Alkali

Steam, Hot Acid

Steam, Hot Water, Hot Acid, Alkali, or Solvent, Hot Air

Sunds Horizontal Screw Reactor

Hastelloy® C-2000 allows pretreatment with other catalysts including hot dilute acid, hot dilute alkali, hot dilute solvents, etc.

Jaygo paddle type batch reactor

Hastelloy® C-22

PneumapressPneumapress®® Automatic Pressure Automatic Pressure Belt FilterBelt Filter

•Hastelloy C-276Semi-continuous filtration system

•Operating pressures up to 180 psig•Temperatures up to 180°C

•3 ft2 filter area design

•Hastelloy C-276Semi-continuous filtration system

•Operating pressures up to 180 psig•Temperatures up to 180°C

•3 ft2 filter area design

•Preheat with 40 psig steam •Slurry chamber fill •Cake wash with 140°C water (175 psig) •Steam blow down with 120 psig steam •Air blow down with hot (>95°C) air (175 psig)

Digestibility of Digestibility of ““Hot WashedHot Washed”” Pretreated Yellow Poplar Pretreated Yellow Poplar from Pilot Scale System from Pilot Scale System

•SSF of Pretreated Yellow Poplar (175°C, 0.7% H2SO4, ~6 min)•Cellulase loading: 20 mg protein/g cellulose (Genencor Spezyme CP) (~5 FPU/g cellulose)

%Ce llu lose Conve rsion (Ave . o f Duplica te F la sks)

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Hot W ater--Low Flow

Horizontal YPC ontrol

Sunds YPC ontrol

SSF Digestibility of SSF Digestibility of ““Hot dilute Ethanol WashedHot dilute Ethanol Washed””Pretreated Yellow Poplar from Pilot ScalePretreated Yellow Poplar from Pilot Scale

%Cellulose Conversion (Ave. of Duplicate Flasks)

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EtO

H (%

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) Hot 0.5%EtOH

Hot 0.2%EtOH

Hot Water--High Flow

Hot Water--Low Flow

Horizontal YPControl

Sunds YPControl

SSF Digestibility of SSF Digestibility of ““Hot dilute Alkali WashedHot dilute Alkali Washed””Pretreated Yellow Poplar from Pilot ScalePretreated Yellow Poplar from Pilot Scale

%Cellulose Conversion (Ave. of Duplicate Flasks)

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Hot 0.2%NaOH

Hot 0.1%NaOH

Hot 0.5%EtOH

Hot 0.2%EtOH

Hot Water--High Flow

Hot Water--Low Flow

Horizontal YPControl

Sunds YPControl

SSF Digestibility of Pilot-Scale “Hot Washed” Corn Stover from Pilot Scale System•SSF of Corn Stover Pretreated in Jaygo Reactor(170°C, 0.5% H2SO4, 8 min)

•Hot washed at ~140°C

•Cellulase loading: 12 mg protein/g cellulose (Genencor Spezyme CP) (~3 FPU/g)

Corn Stover Cellulose Conversion

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al E

TOH

Yie

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LapCtrl.Jaygo HoldHot WaterETOH

Sunds Vertical Hydrolyzer

Zirconium highly resistant to strong acids (i.e. HCl, H2SO4, HNO3, acetic, formic, lactic, etc.) and strong bases

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Initial CS

.2% ETOH

Hot Wash

.1% NaOH

.5% ETOH

SSF Digestibility of Pilot-Scale “Hot Washed” Corn StoverSSF of Sunds Vertical Reactor Pretreated Corn Stover (165°C-190°C, 1% H2SO4, ~5-8 min)

Pretreated solids allowed to cool before hot washing

Hot washed at ~140°C

Cellulase loading: 12 mg protein/g cellulose (Genencor Spezyme) (~3 FPU/g)

Economic Analysis of Hot Wash Economic Analysis of Hot Wash ProcessProcess

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Revised 2003SOT Case

DecreasedPretreatm entTemperature

Hot W ash Added 70%Saccharification

Y ield

80%Saccharification

Y ield

90%Saccharification

Y ield

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10 FPU Enzyme Loading

3 FPU Enzyme Loading

1.5 FPU Enzyme Loading

Commercial Scale ?

Bench Scale

Pilot Scale

Hot Wash Filters

ConclusionsConclusionsIntegrated pilot-scale “hot washing” system installed at NREL.“Hot washing” pretreated YP increased digestibility from 74% to 97% Low enzyme loadings (5-FPU/g of cellulose). “Hot washing” pretreated CS increased digestibility of cellulose from 78% to 90%. Low enzyme loadings (3-FPU/g of cellulose). Lower severity dilute-acid pretreatments of YP and CS gave high enzymatic digestibility of “hot washed”residues.

ConclusionsConclusions“Hot washing” cooled pretreated corn stover

significantly increased the digestibility of the residual cellulose.

Selective washing processes can produce lignin-based co-products.Optimized conditions for Pneumapress solid/liquid

separation could reduce time required for substrate bioconversion.Lower severity pretreatments may be achieved in less

expensive pretreatment reactorsHigh enzymatic digestion of the residual cellulose to

glucose for fermentation to other bio-based products.

AcknowledgementsAcknowledgementsU.S. Department of Energy

Office of the Biomass Program

Steve Benesi, Patrick Costelloe, Tony MillerPneumapress Filter Corp., Richmond, CA