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Synthesis gas from Biomass in Millisecond Reactors

University of Minnesota – Dept. of Chemical Engineering & Materials Science

Paul J. Dauenhauer, Lanny D. Schmidt

American Chemical Society National Meeting

Catalysis and Chemistry for the Synthesis of Fuels, Chemicals, and Petrochemicals

August 20, 2007

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Biomass Processing

H2, CO

Ethanol, Lactic Acid Alkanes

Sugars

Enzymes

Crops (Food, Energy)

Wastes (Agriculture, Municipal)

Alkanes

Methanol

DME

Ethanol

Power

Heat

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Biomass – Aspen Trees

Cellulose (45%)

glucan

O

HO

OCH2OH

HO O

HO

OCH2OH

HO O

HO

OCH2OH

HO O

HO

OCH2OH

HOO

Hemicellulose (21%)

Xylan, Galactan, Arabinan, Mannan)

Lignin (24%)

Extractives (9.5%)

Uronic & acetyl acids

Ash (0.5%)

Yellow - Ca, Mg, K

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0

10

20

30

40

50

60

70

80

90

100

Corn Grain Corn Stover Cane CaneBagasse

Pine Aspen

Ash

Uronic Acids

Extractives

Lignin

Hemicellulose

Cellulose / Algin

What is biomass?

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Fuel and O2 enter at the top

Valuable chemicals produced: syngas (H2 & CO), olefins, oxygenates, etc.

Exothermic process

Runs auto-thermally

Short contact times (Milliseconds)

Fuel + Air

Products

Heat Shields

Catalyst

QuartzTube

Catalytic Partial Oxidation (CPOx)

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“Catalytic Fire”Fuel + O2 CO + H2 + HEAT

Catalyst

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CH4 + 2 O2 CO2 + 2 H2O Combustion

CH4 + 1/2 O2 CO + 2 H2 Partial oxidation

CO + H2O CO2 + H2 Water gas shift

CH4 + H2O CO + 3 H2 Steam reforming

Partial Oxidation of CH4

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Experimental Parameters & Results

2OinOMoles

FuelinCMolesO

C FuelinCMoles

OHMolesCS 2

Experimental Parameters

Experimental Results

FuelofMoles

ConvertedFuelMolesX

FuelconvertedinHofMoles

HproductinHMolesHSH

22 )(

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Partial Oxidation of CH4 - Effluent

• Millisecond residence time

• High Selectivity to H2 and CO

• But what is happening inside?

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Partial Oxidation of CH4 – Profile

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Partial Oxidation of CH4 - Profile

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POx of CH4 + Steam Addition - Profile

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Partial Oxidation of Other Fuels

Volatile

• Methane

• Octane

• up to Hexadecane

• Methanol

• Ethanol

• Propanol

• Ethylene Glycol

• Glycerol

• Ethyl Lactate

Nonvolatile

• Glucose

• Soy Oil

• Cellulose

• Starch

• Lignin

• Polyethylene

• Raw Biomass

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Carbohydrates – CPOx of Glycerol

1. Higher S/C ratios decrease operating temperature

2. Conversion >99% up to C/O=1.6

3. RhCe/γ-Al2O3/α-Al2O3

600

700

800

900

1000

1100

1200

1300

70

75

80

85

90

95

100

0.6 0.8 1 1.2 1.4 1.6 1.8

SC_0_T

SC_2_T

SC_4p5_T

SC_0_T_error

SC_2_T_error

SC_4p5_T_error

SC_0_XSC_2_X

SC_4p5_X

T

(oC)

X(%)

C/O

A

S/C = 0

S/C = 2

S/C = 4.5

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1. Higher S/C ratios increase H2 selectivity

2. Maximum SH(H2)~90% for all three carbohydrates

40

50

60

70

80

90

100

110

120

0.6 0.8 1 1.2 1.4 1.6 1.8

SC_0_S(H)_H2SC_2_S(H)_H2SC_4p5_S(H)_H2SC_0_errorSC_4p5_errorSC_2_errorSC_0_EQSC_2_EQSC_4p5_EQ

SH

(%)

C/O

B

H2

S/C = 4.5

S/C = 2.0

S/C = 0

Carbohydrates – CPOx of Glycerol

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O

HO

OCH2OH

HO O

HO

OCH2OH

HO O

HO

OCH2OH

HO O

HO

OCH2OH

HOO

Carbohydrates

α-D-(+)-Glucose

C6H12O6 or C6(H2O)6

Glycerol

C3H8O3 or C3(H2O)3H2

Boiling Point ~ 300 °C

α

Dehydration Polymerization (C6H10O5 monomers)

α(1-4) – linkage (starches)

highly branched

coiled

β(1-4) – linkage (cellulose)

no branching

linear (crystalline & amorphous)

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Nonvolatile Fuels

How can we reform larger carbohydrates? Pyrolysis

C1 – C4

Volatile Compounds Reform

O2

www.nrel.gov

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Partial Oxidation of CH4

3 mm

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3 mm

Catalytic Reforming of Cellulose

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Cellulose Reforming - Setup

Solids, Air

Air

45 ppi, 5 wt% Rh, Ce

45 ppi, 5wt% WC, 5 wt% Rh, Ce

80 ppi, 5 wt% WC, 5 wt% Rh, Ce

80 ppi, blank

T10

T30

N.J. Degenstein, R. Subramanian, L.D. Schmidt, Applied Catalysis A: General 305 (2006) 146-159.

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Cellulose Reforming - Setup

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0%

10%

20%

30%

40%

50%

60%

70%

200 300 400 500 600 700 800 900 1000 1100 1200

Temperature, 30 mm (deg C)

SC o

r S

H

_ 1.0

Condensing VaporsObserved

0.9

0.8

0.7

C/O

CH4

CO

H2

Operating Temperatures

Cellulose Oxidation - Thermodynamics

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200

400

600

800

1000

1200

0.6 0.7 0.8 0.9 1

Avicel_T_plot_data0.6 0.7 0.8 0.9 1

T1

0

C/O

C/O B

T10

T30

T

(oC)

Carbon

No Carbon

Catalytic Reforming of Cellulose

Always operate predicting no carbon.

P.J. Dauenhauer, B.J. Dreyer, N.J. Degenstein, L.D. Schmidt, Accepted to Angewandte Chemie

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Catalytic Reforming of Cellulose

Produce equilibrium synthesis gas.

Higher C/O = more H2 + CO

Less than 1% methane

At C/O < 1.0, no oxygenates

P.J. Dauenhauer, B.J. Dreyer, N.J. Degenstein, L.D. Schmidt, Accepted to Angewandte Chemie

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Process: Millisecond Catalytic Processing

Cellulose

Gases (ex. CO, H2)

Volatile Organics

Char 200 °C

500 °C

800 °C

Process: Char Production (~minutes)Process: Fast Pyrolysis (~1 sec)Process: Gasification

O2 Rh

O2

X

Cellulose Thermal Decomposition

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C/O: 0.9 0.7

Solid particles contact a hot surface

Particles form volatile organic compounds (VOC)

VOCs undergo exothermic surface oxidation

Heat is conducted upward to drive particle decomposition

Catalytic Reforming of Cellulose

Catalyst

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Catalytic Reforming of Solids

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Cellulose Reforming – Better Syngas

Desire a pure stream of syngas (H2 / CO ~ 2)

• Partially oxidize with pure O2 rather than air

• Reduce convection

• Reduce syngas dilution

• Preheat feed gases

• Operate fuel rich

• Reduce syngas dilution

• Add steam

• Adjust syngas ratio (H2/CO) to ~2

Fuel + O2 + H2O(g)

Products

Heat Shield

Catalyst

QuartzTube

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0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.50

10

20

30

40

50

60

70

80

90

100

Equilibrium Limit

SH (

%)

S/C

>C1 Species Formed

Cellulose Reforming – Steam Addition

C/O

■ 0.6

● 0.7

▼ 0.8

▲ 0.9

79% 59% 39% 19%Feed Gas N2

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600

700

800

900

1000

1100

1200

0.6 0.8 1.0 1.2

T (

o C)

C/O

T (10 mm)

T (30 mm)

0

20

40

60

80

100

0.6 0.8 1.0 1.2

S C or

SH

(%

)

C/O

H2

CO

CO2

<C7=

>C6=

Catalytic Reforming of Polyethylene

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Comparison to Gasification

Faster – 10 to 100X

• Possibly smaller (more portable)

• Faster, more flexible start-up

Cleaner – Catalyst breaks down volatile organics

• Possibly eliminates downstream clean-up stages

Provides WGS capabilities

• Can add steam to adjust H2/CO ratio for desired output

• Possibly eliminates separate shift stage

Remaining Issues

• Ash handling

• Mechanism / Modeling

• High Pressure

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Acknowledgments

Ethanol reforming Tupy, Rennard, Dauenhauer

Olefins from biodiesel Dreyer

Ethyl lactate and ester reforming Rennard, Dauenhauer

Soy oil reforming Dreyer, Dauenhauer

Solids reforming Dauenhauer, Dreyer, Degenstein, Colby

Methanol, ammonia and alkane synthesis Bitsch-Larsen, Huberty, Walker

Ash Management Tupy, Rennard

Professor Lanny D. Schmidt

Dr. Raimund Horn

Professor Ulrike Tschirner

Dr. Raul Caretta

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