Thermochemical Biofuels: Challenges and Opportunities June 14, 2012

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1 Thermochemical Biofuels: Challenges and pportunities June 14, 2012 Brent Shanks Steffenson Professor Chemical & Biological Engineering Department

2 Some Context Petroleum at $90/bbl Gasoline, wholesale & untaxed ~$2.70/gal Diesel, wholesale & untaxed ~$3.00/gal Grain Ethanol, corn at $3 & $6.50/bu $2.40 & $3.80/gge Biofuels Digest, May 11,

3 Technology Comparison* Requires consistent capital cost and evaluation bases Comparative economics, not business-case economics Considered commercial or near-commercial technology where possible Material and energy balances by Aspen Plus, generally Location U.S. Gulf Coast, 2011 $ Biomass at $5.4/GJ (limit 1 million t/yr/plant) Coal at $2/GJ Estimates for N th of a kind plants (N = 5-7) Stand-alone plant: Feedstock in; Finished fuels out Comparisons are based on best available data; design basis and data are often not very complete * Jim Katzer (ExxonMobil retired, Iowa State University) Liquid Transportation Fuels from Coal and Biomass: Technological Status, Costs, and Environmental Impacts, NRC,

4 Biomass Properties & Fuel Cost Component Material: Grain (corn) Corn Stover Wood (poplar) Starch, wt % 72.0 n/m n/m Cellulose, wt % Hemicellulose, wt % Lignin, wt % Ash, wt % Bio-Conversion: Typical Yields: gge/dry tonne Thermal-Conversion: Gasification Yield, gge/dry tonne Pyrolysis Yield, gge/dry tonne Feedstock Cost, $/dry tonne: Feedstock Cost Component: Bioconversion, $/gge 3.50* $2.00 $1.60 Gasification, $/gge - $1.40 $1.10 Fast Pyrolysis, $/gge - $1.75 $1.30 Red numbers are first-cut indicator of feedstock cost contribution to product cost * For Corn at $6.50/bu, DDGS netback reduces this to ~$2.60/gge 4

5 HC Recovery Regenerator Thermochemical: Gasification flue gas Recycle Compr. unconverted syngas + C 1 - C 4 FT gases purge gas Power Island Some Net Electricity net export electricity coal oxygen oxygen ATR steam syngas F-T Synthesis raw FT product syncrude light ends F-T Refining Primarily Finished Gasoline & Diesel finished gasoline & diesel blendstocks Grinding & Slurry Prep water Gasification & Quench slag Syngas Scrubber oxygen steam Water Gas Shift gas expander cooling Acid Gas Removal Refinery H 2 Prod C 2 biomass Chopping & Lock hopper C 2 FB Gasifier & Cyclone dry ash Tar Cracking gas cooling Filter Refrigeration Plant Flash Flash C 2 H 2 S + C 2 To Claus/SCT methanol Coal: all components are commercially robust Biomass gasification is essentially commercial ptions: Methanol synthesis followed by MTG to produce mainly gasoline, DME Liquid Transportation Fuels from Coal and Biomass: Technological Status, Costs, and Environmental Impacts, NRC, 2009.

6 Fuel Component Cost, $/gge Thermochemical: Gasification Feedstock Mode Fuel Price, $/gge Coal (CTL) Vent C Coal CCS 1.90 Coal/Biomass (40%) (CBTL) Vent C Coal/Biomass (40%) CCS 3.00 Biomass (BTL) vent C Biomass CCS Co-produce Recovery C2 Disposal & M Coal Feed Biomass Feed Capital Recovery Fuel Component Cost Liquid Transportation Fuels from Coal and Biomass: Technological Status, Costs, and Environmental Impacts, NRC,

7 Biomass Gasification Challenges Ash management Tars conversion Scalability Reactor technology CompactGTL, Syntroleum Velocys (25 bpd, May, 2012) 7

8 Biomass Fast Pyrolysis* *Bridgwater et al. in Progress in Thermochemical Biomass Conversion, Bridgwater, ed. (2001) 977.

9 Fast Pyrolysis ~500 C + + Corn stover Gas Bio-oil Biochar (~1.5 GJ m -3 ) (~6 MJ kg -1 ) (~22 GJ m -3 ) (~21 MJ kg -1 ) HCH 2 H H CH 2 HCH 2 H H CH 2 Cellulose Gas H 2, C, CH 4, C 2 H 2 Bio-oil. c c..c c. Biochar c.

10 Composition: Fast Pyrolysis Bio-il* Wt% Water Lignin fragments: insoluble pyrolytic lignin Aldehydes: formaldehyde, acetaldehyde, hydroxyacetaldehyde, glyoxal Carboxylic acids: formic, acetic, propionic, butyric, pentanoic, hexanoic Carbohydrates: cellobiosan, levoglucosan, oligosaccharides 5-10 Phenols: phenol, cresol, guaiacols, syringols 2-5 Furfurals 1-4 Alcohols: methanol, ethanol 2-5 Ketones: acetol (1-hydroxy-2-propanone), cyclopentanone 1-5 *Bridgwater et al.; in Progress in Thermochemical Biomass Conversion, Bridgwater, ed. (2001) 977.

11 Thermal Conversion Reactions Primary Processes Secondary Processes Tertiary Processes Vapor Phase C, C 2, H 2 Primary Vapors Light HCs, Aromatics, & xygenates lefins, Aromatics C, H 2, C 2, H 2 PNA s, C, H 2, C 2, H 2, CH 4 C, H 2, C 2, H 2 Low P Liquid Phase Primary Liquids High P Condensed ils (phenols, aromatics) Low P Solid Phase Biomass High Charcoal Coke Soot P Pyrolysis Severity

12 Thermochemical: Pyrolysis Fast pyrolysis Dynamotive, ENSYN Avello Catalytic pyrolysis KIR Anellotech Hydropyrolysis GTI ENSYN, 40 tonne/day KIR, 50 ton/day 12

13 Bio-il Upgrading Approach Biomass Biomass Prep/Pretreatment Selective thermal depolymerization (500º C) Particulate Removal Bio-il Recovery as Stage Fractions Bioasphalt Lignin-derived chemicals Lignin oligomers Anhydro-sugars Water Wash Heavy Ends: Lignin oligomers and anhydrosugars Phenolics and Furans Catalytic deoxygenation ( º C) Ring opening/ deoxygenation ( º C) Hydrogen Steam reforming ( º C) Light Ends: Aqueous phase of low MW carbohydrate-derived compounds Hydrocarbons Hydrocarbons 13

14 Schematic of Pyrolyzer GC/MS System Pyrolyzer Feedstock ~ 500 μg He 500 o C Capillary Separation Column Mass Spectrometer (MS) Gas Chromatograph 14

15 Cellulose Pyrolysis Products Formic acid Acetic acid 3-furan methanol Acetol Furfural 2-furan methanol 5-methyl furfural 5-methyl furfural Hydroxymethylfurfural Glycolaldehyde 2-hydroxy-3-methyl cyclopenten-2-one Levoglucosenone 1,4;3,6-dianhydro-glucopyranose Anhydroxylopyranose Levoglucosan-furanose Levoglucosan Low mol. wt. species Furans/Pyrans Anhydro sugars Patwardhan, P.; et al. J. Anal. Appl. Pyrolysis 2009, 86, 323

16 Effect of Chain Length Glucose Cellobiose Maltohexaose Cellulose LMW Furans Anhydrosugars Levoglucosan All numbers are wt% LMW Low molecular weight compounds Patwardhan, P.; et al. J. Anal. Appl. Pyrolysis 2009, 86,

17 Proposed Mechanism Cellulose Depolymerized fragment Intermediate Another depolymerized fragment Fragment resulting from the Glycosidic cleavage of dextran Levoglucosan Ponder et. al., J Anal. Appl.Pyrolysis,,

18 Department of Chemical and Biological Engineering Detailed mechanism Quantum Chemistry Investigations H H CH + k mid-chain scission - H Initiation k ring closure H + Depropagation H CH + k end-chain scission H Levoglucosan Ponder et al., J. Anal. Appl. Pyrolysis 1992, 22, Mayes and Broadbelt, submitted 18

19 ΔH in kcal/mol at 773K Department of Chemical and Biological Engineering Detailed mechanism Quantum Chemistry Investigations Results Radical Ionic Concerted Concerted Mechanism ΔG in kcal/mol 773K, Implicit THF Gas Implicit THF Implicit Water Mayes and Broadbelt, Unraveling the Reactions that Unravel Cellulose, submitted. 19

20 Department of Chemical and Biological Engineering Reaction pathways included in cellulose fast pyrolysis Pyrolysis Detailed mechanism H H H H H H H H H H H H H H H H H Glucose Levoglucosan is formed by concerted, glycosidic bond cleavage reactions in the mid and end of cellulose chains H H H H H H C H H C H C H C H H H C H C H H C H C H C H C H CH All other low molecular weight products are formed from glucose through various reactions like dehydration, ring opening, ring flipping, retro aldol, retro Diels-Alder and Grob fragmentation H Buy SmartDraw!- purchased copies print this document without a watermark H. H Visit or call H H H H H Char, C 2, C, H 2 HC C H 2 H H H H HC HC HC HC C H 2 CH CH C H C HC H HC CH 2 H HC HC CH HC C H 2 C H C CH CH HC CH CH 2 H HC C H 2 HC HC 20

21 Mass yield, wt.-% Weight loss/mass yield, wt.-% Department of Chemical and Biological Engineering Mass yield, wt.-% Time evolution of products of cellulose fast pyrolysis o C 400 o C 450 o C Cellulose 500 o C 550 o C Levoglucosan T = 500 o C P = 1 atm M n = 135,554 g/mol PDI = Pyrolysis time, s Effect of temperature on cellulose fast pyrolysis products Levoglucosan 5-HMF 2-Furfural Formic acid 350 o C 400 o C 450 o C Experimental data corresponds to Patwardhan et al., Biores. Technol. 2010, 101, o C 550 o C o C 400 o C Glucose 450 o C 500 o C Expt. Model 550 o C HC Pyrolysis time, s o C Model Predictions Glycolaldehyde 400 o C H 2 H C 2 Char MW HMF 2-Furfural 450 o C o C 550 o C

22 Wt % wt % Wt % 60 Alkali/Alkaline Earth Effects Levoglucosan Formic acid 40 NaCl KCl MgCl 2 CaCl mmol of salt/g of cellulose mmol of salt/g of cellulose 4 Acetol 5 Furfural Wt % mmol of salt/g of cellulose mmol of salt/g of cellulose Patwardhan, P.; et al. Bioresource Technol. 2010, 101,

23 mol of glucose/mol of metal ion Effect of Alkali/Alkaline Earth Turnover Number NaCl Ca()2 KCl mmol of salt/g of cellulose Patwardhan, P.; et al. Bioresource Technol. 2010, 101,

24 Proposed Mechanism Ca 2+ Ca 2+ 24

25 Acetic acid Lignin Pyrolysis Low mol. wt. compounds Phenolic compounds Patwardhan, P.; et al. submitted

26 Phenol Methoxy phenol Ethyl phenol Hydroxy styrene Coniferyl alcohol Sinapyl alcohol Micropyrolysis of Lignin Monomers GC-MS Analysis of Vapors from Micropyrolysis of Lignin GC-MS Analysis of Condensed Products from Micropyrolysis of Lignin ligomers Patwardhan, P.; et al. submitted

27 Lignin Monomers coumaryl alcohol coniferyl alcohol sinapyl alcohol 27

28 Area % GPC of Lignin Monomers CCS CCS Mix Mix CCS CCS Mix Mix Py CCS Mix Py CCSA Mix Py Mol. Wt. (Da) Patwardhan, P.; et al. ChemSusChem

29 wt% of biomass (wet basis) Passivating Alkali in Biomass Comparison of Different Switchgrass Pretreatments Switchgrass Control Acetic Acid Formic Acid Nitric Acid Hydrochloric Acid Phosphoric Acid Sulfuric Acid Light xygenates Anhydrosugars Furans Phenols Kuzhiyil et al. (2012) submitted 29

30 Biochar Application Increases: Nutrient Availability Microbial Activity Soil rganic Matter Water Retention & Quality Crop Yields Terra Preta xisol Decreases: Fertilizer Needs Greenhouse Gas Emissions Nutrient Leaching Soil Bulk Density 30

31 Carbon Residence Time 100 m 31

32 Biochar Average Structure Moderate Temperature High Temperature Brewer, et al. Environ. Prog. Sustainable Energy 2009, 28,

33 Key Challenges Gasification issue of scale Pyrolysis issue of product quality 33

34 Robert Brown Jim Katzer Pushkaraj Patwardhan Klaus Schmidt-Rohr Catherine Brewer Linda Broadbelt Vinu Ravikrishnan Heather Mayes Acknowledgements ConocoPhillips U.S. Department of Energy National Advanced Biofuels Consortium 34