360 likes | 573 Views
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
E N D
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
Biomass Processing Ethanol, Lactic Acid Alkanes Enzymes Sugars Alkanes Methanol DME Ethanol Power Heat H2, CO Crops (Food, Energy) Wastes (Agriculture, Municipal)
Lignin (24%) Hemicellulose (21%) Xylan, Galactan, Arabinan, Mannan) Extractives (9.5%) Uronic & acetyl acids Cellulose (45%) glucan Ash (0.5%) Yellow - Ca, Mg, K Biomass – Aspen Trees
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 Quartz Tube Heat Shields Catalyst Products Catalytic Partial Oxidation (CPOx)
“Catalytic Fire” Fuel + O2CO + H2 + HEAT Catalyst
Partial Oxidation of CH4 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
Experimental Parameters & Results Experimental Parameters Experimental Results
Partial Oxidation of CH4 - Effluent • Millisecond residence time • High Selectivity to H2 and CO • But what is happening inside?
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
Carbohydrates – CPOx of Glycerol • Higher S/C ratios decrease operating temperature • Conversion >99% up to C/O=1.6 • RhCe/γ-Al2O3/α-Al2O3
Carbohydrates – CPOx of Glycerol S/C = 4.5 • Higher S/C ratios increase H2 selectivity • Maximum SH(H2)~90% for all three carbohydrates S/C = 2.0 S/C = 0
Carbohydrates α Glycerol C3H8O3 or C3(H2O)3H2 Boiling Point ~ 300 °C α-D-(+)-Glucose C6H12O6 or C6(H2O)6 Dehydration Polymerization (C6H10O5 monomers) α(1-4) – linkage (starches) highly branched coiled β(1-4) – linkage (cellulose) no branching linear (crystalline & amorphous)
O2 C1 – C4 Volatile Compounds Reform Nonvolatile Fuels How can we reform larger carbohydrates? Pyrolysis www.nrel.gov
Solids, Air Air 45 ppi, 5 wt% Rh, Ce T10 80 ppi, 5 wt% WC, 5 wt% Rh, Ce 45 ppi, 5wt% WC, 5 wt% Rh, Ce T30 80 ppi, blank Cellulose Reforming - Setup N.J. Degenstein, R. Subramanian, L.D. Schmidt, Applied Catalysis A: General305 (2006) 146-159.
7 0 % CO C o n d e n s i n g V a p o r s O b s e r v e d 6 0 % 5 0 % C / O 1 . 0 _ 4 0 % 0 . 9 H or S CH4 3 0 % 0 . 8 C S 0 . 7 2 0 % H2 Operating Temperatures 1 0 % 0 % 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0 7 0 0 8 0 0 9 0 0 1 0 0 0 1 1 0 0 1 2 0 0 T e m p e r a t u r e , 3 0 m m ( d e g C ) Cellulose Oxidation - Thermodynamics
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
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
Cellulose Thermal Decomposition Gases (ex. CO, H2) O2 Rh 800 °C Cellulose Volatile Organics O2 500 °C X Char 200 °C Process: Millisecond CatalyticProcessing Process: Char Production (~minutes) Process: Gasification Process: Fast Pyrolysis (~1 sec)
Catalytic Reforming of Cellulose 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 Catalyst C/O: 0.9 0.7
Cellulose Reforming – Better Syngas Fuel + O2 + H2O(g) • 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 Quartz Tube Catalyst Heat Shield Products
Cellulose Reforming – Steam Addition C/O ■ 0.6 ● 0.7 ▼ 0.8 ▲ 0.9 Feed Gas N2 79% 59% 19% 39%
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
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