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Millisecond Catalytic Conversion of Nonvolatile Carbohydrates for Sustainable Fuels
University of Minnesota – Dept. of Chemical Engineering & Materials Science
Paul J. Dauenhauer, Bradon J. Dreyer, Josh L. Colby, Lanny D. Schmidt
American Chemical Society National Meeting
Division of Fuel ChemistryBiofuels: Renewable Liquid Fuels
& Chemicals from Biomass
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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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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Experimental Setup
Air
FuelInjector
Plug
Upstream Temperature
Incinerator
Sample Port
Catalyst
Static Mixer
Backface Temperature
Heating Tape
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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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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
80 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 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
Catalytic Reforming of Cellulose
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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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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
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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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