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Ammonia Fiber Explosion (AFEX) for Pretreatment of Corn Stover: Recent Research Results

Ammonia Fiber Explosion (AFEX) for Pretreatment of Corn Stover: Recent Research Results. Farzaneh Teymouri, Hasan Alizadeh, Lizbeth Laureano-Perez and Bruce E. Dale Department of Chemical Engineering & Materials Science Michigan State University AIChE Annual Meeting

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Ammonia Fiber Explosion (AFEX) for Pretreatment of Corn Stover: Recent Research Results

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  1. Ammonia Fiber Explosion (AFEX) for Pretreatment of Corn Stover: Recent Research Results Farzaneh Teymouri, Hasan Alizadeh, Lizbeth Laureano-Perez and Bruce E. Dale Department of Chemical Engineering & Materials Science Michigan State University AIChE Annual Meeting San Francisco, California November 20, 2003 Biomass Refining CAFI

  2. Biomass Refining CAFI Ammonia Ammonia Gaseous Gaseous Recovery Recovery Liquid Liquid Ammonia Ammonia Ammonia Ammonia Treated Treated Biomass Biomass Biomass Biomass Reactor Reactor Explosion Explosion What is AFEX/FIBEX? • Liquid ammonia treats, explodes biomass, 99% of ammonia is recovered & reused, remainder serves as N source downstream? • No 1) fermentation inhibitors, 2) wash stream required, 3) overliming • Conditions: 60-100 C, moisture 20-60%, ammonia:biomass ratio 0.5-1.0:1.0 (dry basis), pressure up to 250 psig give theoretical yields for glucose and nearly 80% of theoretical for xylose • Few visible effects of pretreatment, material is left dry and can be fed at very high solids loadings, stable for long periods

  3. The “Big Four” Process Parameters • Yield (mass desired product(s) per mass purchased raw material) • Concentration (mass desired product(s) per unit reactor volume) • Purity (ratio of desired product concentrations to undesired products in the final reaction mixture) • Rate (desired product(s) produced per unit reactor volume per unit time) • How does AFEX stack up on the “Big Four?” Biomass Refining CAFI

  4. AFEX Parameters Affecting Sugar Yields • Primary focus of IFAFS project, these are: • Ammonia:biomass ratio • Temperature (also affects pressure) • Moisture content of biomass • Enzyme loading (FPU per gram glucan) • Approximate “optimal” conditions for corn stover: 1:1 ammonia:biomass ratio, 90 degrees C, moisture content 60% dwb • Enzyme loading is highly variable—we get effective hydrolysis at 7.5 FPU gram glucan • We need better enzymes; especially for alkaline pretreatments • Lots of data—we only show part of it Biomass Refining CAFI

  5. Conversion of Glucan and Xylan vs. AFEX Treatment Temperature Biomass Refining CAFI

  6. Effect of Ammonia Loading on Glucan & Xylan Conversion @ 60 FPU/gm glucan Biomass Refining CAFI

  7. Conversion of Glucan and Xylan vs. Moisture Content at 90 0C Biomass Refining CAFI

  8. Hydrolysis of Stover Glucan & Xylan At Two Enzyme Levels Treatment Conditions: 90 °C, 60% Moisture, 1:1 Ammonia:Biomass 5 minutes treatment Biomass Refining CAFI

  9. AFEX Process Yields & Mass Balance Enzyme (15 FPU/g of Glucan) Ammonia Hydrolyzate 99.0 lb AFEX Stover Treated Liquid Hydrolysis Wash 38.5 lb glucose Stover System 100 lb (Ave. of 4 runs) 18.9 lb xylose 101.0 lb Residual (dry basis) Solids Solids washed out 36.1 lb glucan 2 lb 38.7 lb 21.4 lb xylan 95.9% glucan conversion, 77.6% xylan conversion 94% mass balance closure includes (corrected for water of hydrolysis): (solids + glucose + xylose + arabinose ) Biomass Refining CAFI

  10. The “Big Four” Process Parameters • Yield (mass final product per mass purchased raw material) • Concentration (mass product per unit reactor volume) • Purity (ratio of primary product concentration to other products in the reaction mixture) • Rate (product produced per unit reactor volume per unit time) • How does AFEX stack up on the “Big Four?” Biomass Refining CAFI

  11. AFEX Process Yields & Mass Balance Enzyme (15 FPU/g of Glucan) Ammonia Hydrolyzate 99.0 lb AFEX Stover Treated Liquid Hydrolysis Wash 38.5 lb glucose Stover System 100 lb (Ave. of 4 runs) 18.9 lb xylose 101.0 lb Residual (dry basis) Solids Solids washed out 36.1 lb glucan 2 lb 38.7 lb 21.4 lb xylan 95.9% glucan conversion, 77.6% xylan conversion 94% mass balance closure includes (corrected for water of hydrolysis): (solids + glucose + xylose + arabinose ) Biomass Refining CAFI

  12. Water Loadings and Stover Solids Made Soluble by Pretreatments

  13. Some Distinctive Features of AFEX NOT MUCH CHANGE IN APPEARANCE- DRY PROCESS HPLC at 168 hours Stover hydrolysis- 15 FPU @ zero hrs. Glucose, xylose, arabinose, Not much else CLEAN SUGAR STREAMS FOR FERMENTATION AFEX treated Untreated Biomass Refining CAFI NOT MUCH EXTRACTED FROM TREATED STOVER

  14. Fed Batch SSF of AFEX Treated and Untreated Corn Stover (15 IU/gm glucan) Untreated stover in SSF 24% solids loading AFEX treated stover in fed batch SSF at 24% solids loading Doesn’t flow worth a dang Flows very easily Dark appearance is deceptive- caused by autoclaving & media Biomass Refining CAFI

  15. The “Big Four” Process Parameters • Yield (mass final product per mass purchased raw material) • Concentration (mass product per unit reactor volume) • Purity (ratio of primary product concentration to other products in the reaction mixture) • Rate (product produced per unit reactor volume per unit time) • How does AFEX stack up on the “Big Four?” Biomass Refining CAFI

  16. Kinetics of Glucan Hydrolysis Biomass Refining CAFI

  17. Hydrolysis of Stover Glucan & Xylan At Two Enzyme Levels Treatment Conditions: 90 °C, 60% Moisture, 1:1 Ammonia:Biomass 5 minutes treatment Biomass Refining CAFI

  18. AFEX Process Yields & Mass Balance Enzyme (15 FPU/g of Glucan) Ammonia Hydrolyzate 99.0 lb AFEX Stover Treated Liquid Hydrolysis Wash 38.5 lb glucose Stover System 100 lb (Ave. of 4 runs) 18.9 lb xylose 101.0 lb Residual (dry basis) Solids Solids washed out 36.1 lb glucan 2 lb 38.7 lb 21.4 lb xylan 95.9% glucan conversion, 77.6% xylan conversion 94% mass balance closure includes (corrected for water of hydrolysis): (solids + glucose + xylose + arabinose ) Biomass Refining CAFI

  19. A Few More Words on Yield • Yield (mass final product per mass purchased raw material) • Sugar is an intermediate product, but not the final product we desire • We have fermentation yield information on AFEX-treated materials, here is some of it Biomass Refining CAFI

  20. Ethanol from Enzyme Hydrolyzates of AFEX Pretreated Corn Fiber Organism Maximum Ethanol Ethanol Yield % Theoretical • Glucose & xylose were both well-utilized by all three organisms • Hydrolyzates were fermented “as is” without dilution • No removal of degradation products (none were detected) • Work done by Dr. M. Moniruzzaman in conjunction with Dr. Nancy Ho, Dr. Lonnie Ingram and Dr. Rod Bothast’s group (g/L) (g/g sugar) Ethanol Yield E. Coli SL 40 26.6 0.46 90 E. Coli KO 11 27.1 0.47 92 Saccharomyces strain 1400 21.0 0.50 95 (pLNH 32) Biomass Refining CAFI

  21. Some Conclusions & Observations I • Maximum glucose yield to date approx. 100% of theoretical, xylose yield approx. 80% from AFEX corn stover • Very high solids “concentrations” achievable during hydrolysis and fermentation of AFEX material • Both glucose and xylose are converted to ethanol at high yields by engineered yeast and bacteria • Not much difference between 60 & 15 FPU/gm; difference diminishes with increasing temperature Biomass Refining CAFI

  22. Some Conclusions & Observations II • Have not “tuned” AFEX pretreatment for lower enzyme levels, or better enzyme mixtures • Increasing ammonia loadings, temperatures, moisture loadings all enhance effects of AFEX; therefore less need for enzyme • Xylanase seems much less effective than glucanase—at least on this substrate for this pretreatment • Developing enzyme mixture(s) for specific pretreatments & specific substrates deserves much more attention—enzyme, pretreatment and fermentation development should proceed together Biomass Refining CAFI

  23. Future Work • AFEX studies: • Tune AFEX for 7.5 IU/gram glucan • Complete SSF studies on stover • Begin looking at other enzyme cocktails • Begin participation in CAFI 2 • Continue analytical work & modeling to develop fundamental insights on pretreatment effectiveness: • X Ray diffraction • Infrared analysis • Fluorescence studies Biomass Refining CAFI

  24. Acknowledgements • The USDA Initiative for Future Agricultural and Food Systems Program through contract 00-52104-9663 • National Renewable Energy Laboratory Biomass Refining CAFI

  25. Questions ?? Biomass Refining CAFI

  26. Specific Goals at Michigan State • Better understand performance of AFEX system • Investigate interplay between treatment conditions (temperature, moisture content, ammonia:biomass levels, time) • Analyze AFEX pretreated corn stover and evaluate its digestibility by enzymatic hydrolysis & fermentation • Optimize AFEX pretreatment for corn stover based on sugar yields from glucan & xylan • Provide analysis to the IFAFS group for cellulose crystallinity, fluorescence and IR to enhance our fundamental understanding of pretreatment effectiveness Biomass Refining CAFI

  27. AFEX Process Yields & Mass Balance Enzyme (60 FPU/g of Glucan) Ammonia Hydrolyzate 98.5 lb AFEX Stover Treated Liquid Hydrolysis Wash 39.9 lb glucose Stover System 100 lb (Ave. of 3 runs) 19.3 lb xylose 100.5 lb Residual (dry basis) Solids Solids washed out 36.1 lb glucan 2 lb 35 lb 21.4 lb xylan 99.4% glucan conversion, 79.4% xylan conversion (up-dated on 9/10/03) 98% mass balance closure includes: (solids + glucose + xylose + arabinose ) Biomass Refining CAFI

  28. AFEX Process Yields & Mass Balance Enzyme (7.5 FPU/g of Glucan) Ammonia Hydrolyzate 98.5 lb AFEX Stover Treated Liquid Hydrolysis Wash 34.2 lb glucose Stover System 100 lb (Ave. of 2 runs) 14.42 lb xylose 100.5 lb Residual (dry basis) Solids Solids washed out 36.1 lb glucan 2 lb TBD 21.4 lb xylan 85.3% glucan conversion, 59.3% xylan conversion (up-dated on 9/10/03) Biomass Refining CAFI

  29. Ammonia Fiber Explosion (AFEX) System Biomass Refining CAFI

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