Design and Scale-Up of Corn Fiber and Corn Stover Pretreatment for Fuel

Ethanol Production

Nathan Mosier, Rick Hendrickson, Bruce Dien, Rich Dreschel, Gary Welch, Michael Ladisch

Purdue University

Williams Bio-energy

USDA NCAUR

IFAFS Project Institutions

Acknowledgements

The material is this work was supported by:

USDA Initiative for Future Agricultural and Food Systems/Cooperative State Research,

Education and Extension Service Contract 00-52104-0663

NREL Subcontract ZCO-1-31023-01

Purdue University Agricultural Research Programs

Acknowledgements

Andy Aden

Bruce Dale

Tim Eggeman

Rick Elander

Joan Goetz

Mark Holtzapple

Kelly Ibsen

Young Mie Kim

Y.Y. Lee

Charles Wyman

Where does corn fiber come from?

What is corn stover?

Stalks

Leaves

Cobs

Roots

Typical Compositions

Glucan (cellulose) 36.2% 14.3%

Glucan (starch) 0.0 23.7

Xylan 21.4 16.8

Arabinan 3.9 10.8

Protein 3.5 11.8

Lignin 22.6 8.4

Acetyl 2.3 NA

Ash 6.0 0.4

Corn Stover Corn Fiber

Crystalline Region

Amorphous Region

CelluloseLignin

Hemicellulose

Effect of Pretreatment

Pretreatment

Pretreatment Modeling

C

C*

Gn G Degradation

k1

k2

k3k4

K

k2, k3, >> k1

Principles of Liquid Water Pretreatment

1. Controlled pH

2. High Temperature

3. Liquid Water (high pressure)– Water acts as acid

• kw = 10-14 to 6 • 10-12 from 20°C to 230°C.

pH of Liquid Water vs Temperature

5

5.5

6

6.5

7

7.5

0 50 100 150 200 250 300 350

Temperature (oC)

pH Minimum

pH 5.62 at 230oC

pH 5.66 at 190oC

Pretreatment Modeling

C

C*

Gn G Degradation

k1

k2

k3k4

K

Utilization of FiberBenefits of existing industrial infrastructure

Fiber already collected:

fiber packaged with corn

Existing ethanol plants:

handle and manage fiber streams

provide utilities

process fermentation ethanol

market ethanol and co-products

Process DescriptionPretreated Corn Fiber: Liquid Separation

Fiber Pretreat

Centrifuge

To Fermentation

Solids

LiquidStillage

“Snake-coil” Plug Flow Pretreatment Reactor

Williams Bioenergy

Pekin, IL

Process StepsLiquid / Solid Separation and SSF

1. Separate liquid from solids with centrifuge

2. Process liquid stream

Add cellulase, other enzymes.

Combine with liquified starch stream.

Add yeast.

Hydrolyze, ferment in the same tank.

3. Process solids from pretreatment

Dry and sell as co-product feed.

Pretreatment Conditions

Fiber : Stillage Ratio

wet basis = 0.39 : 1

Fiber : Water Ratio

dry basis = 0.16 : 1

Temperature and Hold Time

160 C, hold for 30 min

Separate liquid from solid (centrifuge)

Liquid to fermentor, solid to feed drier

Pretreated Corn Fiber

Amylase80 U Amylase + 6.3 kU

Amyloglucosidase per g biomass

Cellulase10 FPU/g biomass

(Celluclast + Novozyme 188)

Glucose1 (g/g)

0.0043 0.42

Yield2 (%) 1.3% 100%

1 – grams of free glucose per gram of pretreated fiber

2 – based on analysis of pretreated fiber by 4% acid hydrolysis

FermentabilityHydrolyzed Pretreatment Liquid

0

5

10

15

20

25

30

35

40

45

0 2 4 6 8 10 12 14

Time (hrs)

Co

nce

ntr

atio

n (

g/L

)

Glucose

Ethanol

Data from Nacy Ho and Miroslav Sedlak, LORRE, Purdue University

Fermentability confirmed by Bruce Dien, USDA-NCAUR

Corn Fiber / Stover UtilizationOpportunities

Increase annual ethanol production by100 million gal/ yr or more

Introduce cellulose conversion technologies into existing corn to ethanol facilities

Catalyze industry use of other cellulosics

Corn Stover Pretreatment

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

0 5 10 15 20 25Pretreatment Time (min.)

So

lub

iliz

ati

on

(%

)

200°C190°C180°C170°C

Corn Stover (1000x)

Pretreated Corn Stover (1000x)

Xylose RecoverypH 4.5, 50°C, Celluclast + Novozyme 188, 96 hrs

10

20

30

40

50

60

70

80

0 5 10 15 20 25Pretreatment Time (min.)

Xyl

ose

/Gal

acto

se Y

ield

(%

)

200 °C190 °C180 °C170 °C

Corn Stover DigestibilitypH 4.5, 50°C Celluclast + Novozyme 188, 96 hrs

10

20

30

40

50

60

70

80

0 5 10 15 20 25Pretreatment Time (min.)

Glu

cos

e Y

ield

(%

)

200 °C190 °C180 °C170 °C

Conclusions

Conversion of Corn Fiber and Corn Stover gives fermentable sugars

Pretreatment required

Water is an effective pretreating agent

pH control minimizes monosaccharide formation

Industrial pretreatment development and pilot research being underway

Fermentability

0

5

10

15

20

0 10 20 30 40 50 60 70 80

1 CSL & 0 PCF (Control)1/2 PCF & 1/2 CSL1 PCF & 0 CSL

Time (hr)

Wei

ght L

oss

(gra

ms)

Corn Steep Liquor (Control) vs

Pretreated Corn Fiber

CO

2 P

rodu

ced

Integrated Biomass Integrated Biomass ProcessingProcessing

Milling

Fiber Separation

Saccharification

Gluten Separation

Gluten

Fermentation

Distillation

Ethanol

FiberFiberStillageStillage

DryerAnimal

FeedPretreatment

Saccharification

DryerAnimal

Feed

Ethanol

Utilization of FiberChallenges

Limited markets as animal feed

Relatively low price at $60 to 65 /ton

Triple bioenergy production by 2010 will generate more fiber

Comparison of Pretreatment Liquid and Stillage

0

20000

40000

60000

80000

100000

120000

140000

0 5 10 15 20 25 30 35 40 45 50 55 60

Time (min.)

Res

po

nse

(m

V)

Pretreatment10x Dilute

Stillage10x Dilute

Bio-Rad HPX-87H 300mm x 7.8mm HPLC Column

5mM H2SO4 Buffer60oC, 0.6 mL/min

Corn Fiber Pretreatment

Lignin

Starch

Xylan

Corn Fiber

Pretreatment Solid

Pretreatment Liquid

14%

24%

17%

8%

Cellulose

Lignin

CelluloseStarch

Xylan

Glucose

Xylan

Xylose

19%

36%

3%

20%

12%Protein

Protein

2.6%

1.0%

0.1%

0.6%

Concentration (%w/w)

Composition (% dry wt)

Composition (% dry wt)