Progress 10/01/02 to 09/30/03
Outputs
The project is on schedule. The Agricultural and Industrial Advisory Board was expanded some to 16 members, and the Team met twice with them to obtain feedback. The Team held conference calls to coordinate throughout the year. Corn stover was used as the feedstock for all tests. Auburn University reduced liquid rates to 3.3 mL/g of stover for Ammonia Recycled Percolation (ARP) pretreatment. Auburn also developed a new SAA pretreatment method at moderate conditions of <100C and atmospheric pressure. Advantages are the process is simple, most hemicellulose is retained, and process energy and equipment costs are low. It was also proven that recombinant E. coli can efficiently utilize both the glucan and the xylan in treated corn stover. Dartmouth College achieved 90% total sugar yields for batch dilute acid pretreatment followed by enzymatic hydrolysis at high loadings. The optimum conditions for these steps were not the same, and enzymes enhanced xylose recovery. Models
were devised to predict high temperature pH and describe oligomer and monomer release. Hemicellulose removal increased significantly with water flow through biomass, contrary to customary predictions, and possible mechanisms were developed. A novel periodic-flow was developed to reduce water use but enhance performance. Michigan State University optimized ammonia fiber explosion (AFEX) to convert cellulose and hemicellulose to glucose and xylose and realized near theoretical yields of glucose and about 80% yields of xylose. Over 90% yields of glucose resulted at lower enzyme loadings of 7.5 IU/gram glucan. MSU also provided infrared, fluorescence, and X ray diffraction analysis for all team members. MBI International is pursuing scale up and commercialization of AFEX with interested parties. Purdue University optimized their controlled pH process at 190C with pH control at 4-7 through liquid buffer capacity to minimize monosaccharides and avoid their degradation to inhibitors that
affect fermentation. Controlled pH pretreatment of stover resulted in 87% of glucan and 78% of xylan being hydrolyzed at a cellulase loading of 15 FPU/g pretreated corn stover, and 88% of the glucose and xylose was converted to ethanol by a recombinant yeast developed at Purdue. Texas A&M University treated corn stover with lime and air at 25-55C for up to 16 weeks. The optimal conditions were 4 weeks with 0.1 g of lime/g biomass at 55C. At an enzyme loading of 15 FPU/g glucan, 92.4% of glucan and 78.4% of xylan were hydrolyzed. At an enzyme loading of 60 FPU/g glucan, 97.1% of glucan and 81.0% of xylan were hydrolyzed. This lime/air treatment has been licensed to Terrabon, LLC who is raising $2 million to construct a demonstration plant. The National Renewable Energy Laboratory (NREL) participated through Department of Energy funding and continued to store and supply corn stover and cellulase. Process and economic models were also updated for each pretreatment with performance and
digestibility data from each researcher. In addition, NREL conducted comparative simultaneous saccharification and fermentation studies on samples from each pretreatment process.
Impacts
Cellulosic biomass is a unique sustainable resource for making organic fuels and chemicals. Very low greenhouse gas emissions is a powerful attribute, but cellulosic biomass use would also enhance energy security, reduce trade deficits, create rural employment, and dispose of waste. Cost and availability of cellulosics are attractive, and the primary need is to reduce processing costs. Pretreatment is essential for biological conversion, and the project is developing comparable information on leading pretreatments that would open up major new agricultural markets. Data and projected costs are compared and widely disseminated, and opportunities are sought to accelerate commercial applications. An Agricultural and Industrial Advisory Board gains insight and provides guidance in regular meetings. The project gives significant momentum to biomass processing as well as important educational benefits. Key findings are emerging through this project. First, each pretreatment
provides highly digestible cellulose, with about 90% of the cellulose converted to glucose. The project also shows that hemicellulase activity in enzyme increases hemicellulose sugar yields, particularly for high pH pretreatment technologies. The initial economic analysis has projected similar costs for all processes, but further integration and optimization is ongoing to more fully capture the unique features of each pretreatment. A number of papers, patent applications, and presentations resulted, and several companies are working with participants to commercially apply pretreatment technologies.
Publications
- Kim TH, Sunwoo C, Lee YY. 2003. "Pretreatment of corn stover by aqueous ammonia," Bioresource Technology 90: 39-47.
- Lee YY, Kim TH. 2003. "Low-temperature treatment of lignocellulosic biomass with aqueous ammonia for improvement of enzymatic digestibility," US Provisional Patent Application 60/459,670, April 20.
- Mosier N, Wyman CE, Dale BE, Elander RT, Lee YY, Holtzapple M, Ladisch MR. 2003. "Features of promising technologies for pretreatment of lignocellulosic biomass," Bioresource Technology (submitted).
- Kim TH, Lee YY. 2004. "Fractionation of corn stover by hot-water and aqueous ammonia treatment," Bioresource Technology (submitted).
- Liu C, Wyman CE. 2004. "The effect of flow rate of very dilute sulfuric acid on xylan, lignin, and total mass removal from corn stover," Industrial Engineering Chemistry Research (accepted).
- Liu C, Wyman CE. 2004. "Impact of fluid velocity on hot water pretreatment of corn stover in a flowthrough reactor," Applied Biochemistry and Biotechnology (Proceedings of the 25th Symposium on Biotechnology for Fuels and Chemicals), (in press).
- Lloyd TA, Wyman CE. 2004. "Predicted effects of mineral neutralization and bisulfate formation on hydrogen ion concentration for dilute sulfuric acid pretreatment," Applied Biochemistry and Biotechnology (Proceedings of the 25th Symposium on Biotechnology for Fuels and Chemicals), (in press).
- Kim TH, Lee YY. 2003. "Pretreatment of corn stover by soaking in aqueous ammonia," AIChE Annual Meeting, San Francisco, CA, November (proceedings and oral presentation).
- Laureno-Perez L, Teymouri F, Dale B, Alizadeh H. 2003. "Understanding factors that limit enzymatic hydrolysis of biomass: Characterization of pretreated corn stover," AIChE Annual Meeting, San Francisco, CA, November (proceedings and oral presentation).
- Liu C, Wyman CE. 2002. "Comparison of batch and flowthrough biomass pretreatment systems for biological production of fuels and chemicals," 12th European Biomass Conference and Exhibition, Amsterdam, The Netherlands, June (poster and proceedings paper).
- Dale BE, Laureano-Perez L. 2002. "Spectroscopic characterization of pretreated corn stover," 24th Symposium on Biotechnology for Fuels and Chemicals, Gatlinburg, TN, April (poster).
- Kim TH, Lee YY. 2002. "Fractionation of corn stover by a two-stage percolation process," 24th Symposium on Biotechnology for Fuels and Chemicals, Gatlinburg, TN (poster).
- Liu C, Wyman CE. 2002. "Effect of flow rate on the dissolution of hemicellulose, lignin, and total mass for pretreatment of corn stover in a flowthrough reactor," 24th Symposium on Biotechnology for Fuels and Chemicals, Gatlinburg, TN, May (poster).
- Lloyd TA, Wyman CE. 2002. "Application of a depolymerization model for predicting thermochemical hemicellulose hydrolysis," 24th Symposium on Biotechnology for Fuels and Chemicals, Gatlinburg, TN, May (presentation).
- Teymouri F, Dale BE. 2002. "Effects of pretreatment on the activity of enzymes in plants: cellulase enzymes and ribulose diphosphate carboxylase," 24th Symposium on Biotechnology for Fuels and Chemicals, Gatlinburg, TN, May (presentation).
- Liu C, Wyman CE. 2003. "Comparsion of batch, stop-flow-stop, and flowthrough pretreatment of corn stover," AIChE Annual Meeting, San Francisco, CA, November (proceedings and oral presentation).
- Lloyd TA, Wyman CE. 2003. "Application of a depolymerization model for predicting thermochemical hemicellulose hydrolysis," Applied Biochemistry and Biotechnology (Proceedings of the 24th Symposium on Biotechnology for Fuels and Chemicals) 105-108: 53-67.
- Eggeman T, Elander R, Ibson K. 2003. "Logistical support and modeling efforts in pretreatment research," AIChE Annual Meeting, San Francisco, CA, November (proceedings and oral presentation).
- Kim S, Thanakoses P, Holtzapple MT. 2003. "Lime pretreatment," AIChE Annual Meeting, San Francisco, CA, November (proceedings and oral presentation).
- Lloyd TA, Wyman CE. 2003. "Overall sugar yields from corn stover via thermochemical hemicellulose hydrolysis followed by enzymatic hydrolysis," AIChE Annual Meeting, San Francisco, CA, November (proceedings and oral presentation).
- Mosier N, Hendrickson R, Kim Y, Zeng M, Dien B, Welch G, Wyman CE, Ladisch MR. 2003. "Optimization of controlled pH liquid hot water pretreatment of corn fiber and stover," AIChE Annual Meeting, San Francisco, CA, November (proceedings and oral presentation).
- Teymouri F, Laureano-Perez L, Dale B, Alizadeh H. 2003. "Ammonia fiber explosion (afex) for pretreatment of corn stover: recent research results," AIChE Annual Meeting, San Francisco, CA, November (proceedings and oral presentation).
- Wyman CE, Dale B, Eggeman T, Elander R, Holtzapple M, Ladisch M, Lee YY. 2003. "Comparison of selected results for application of leading pretreatment technologies to corn stover," AIChE Annual Meeting, San Francisco, CA, November (oral presentation).
- Wyman CE, Eggeman T. 2003. "Pretreatment of lignocellulosic biomass: update on biomass refining cafi studies," AIChE Annual Meeting, San Francisco, CA, November (oral presentation).
- Dale BE, Elander RT, Holtzapple M, Ladisch MR, Lee YY, Eggeman T, Wyman CE. 2003. "Comparative data from application of leading pretreatment technologies to corn stover," 25th Symposium on Biotechnology for Fuels and Chemicals, Breckenridge, CO, May (oral presentation).
- Hendrickson R, Mosier NS, Ladisch MR. 2003. "Generation of coproducts derived from a modified hot water pretreatment of corn stover," 25th Symposium on Biotechnology for Fuels and Chemicals, Breckenridge, CO, May (poster).
- Kim TH, Lee YY. 2003. "Pretreatment of corn stover by low-liquid ammonia percolation process," 25th Symposium on Biotechnology for Fuels and Chemicals, Breckenridge, CO, May (poster).
- Kim TH, Lee YY. 2003. "Effect of lignin on enzymatic hydrolysis of cellulose," 25th Symposium on Biotechnology for Fuels and Chemicals, Breckenridge, CO, May (poster).
- Liu C, Wyman CE. 2003. "Impact of fluid velocity and contact time on corn stover pretreatment in a flowthrough reactor," 25th Symposium on Biotechnology for Fuels and Chemicals, Breckenridge, Colorado, May 5 (poster).
- Kim YM, Mosier NS, Hendrickson R, Goetz J, Ladisch MR. 2003. "Hydrolysis of oligosaccharides using strong cation exchange catalyst and cellulase enzymes," ACS National Meeting, New Orleans, March 25 (poster).
- Mosier NS, Hendrickson R, Welch G, Ladisch CM, Ladisch MR. 2002. "Design and scale-up of corn fiber and corn stover pretreatment for fuel ethanol production," AIChE Annual Meeting, Indianapolis, IN, November.
- Dale B, Wyman CE, Elander RT, Holtzapple MT, Ladisch MR, Lee YY. 2002. "Recent activities of the Consortium for Applied Fundamentals and Innovation," AIChE Annual Meeting, Indianapolis, IN, November 4 (presentation).
- Kim TH, Sunwoo C, Lee YY. 2002. "Pretreatment and fractionation of corn stover by aqueous ammonia," AIChE Annual Meeting, Indianapolis, IN, November (proceedings and oral presentation).
- Liu C, Wyman CE. 2002. "Evaluation of a flowthrough reactor for corn stover pretreatment," AIChE Annual Meeting, Indianapolis, IN, November (proceedings and oral presentation).
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Progress 10/01/01 to 09/30/02
Outputs
The project is on schedule. The Agricultural and Industrial Advisory Board was expanded to 15 members, and the Team met twice with them, as targeted, to obtain feedback. The Team held conference calls to coordinate research throughout the year. Auburn University continued to develop Ammonia Recycled Percolation (ARP) pretreatment based on aqueous ammonia. ARP is very effective in removing lignin, and cellulase enzyme activities digested both the hemicellulose and cellulose in ARP treated solids. Hot-water treatment followed by ARP gave three constituents, and the resulting digestibility was comparable to that for just ARP. Although enzymatic digestibility was strongly affected by lignin content, crystallinity had little effect. Dartmouth College achieved more than 90% sugar yields for batch pretreatment by hemicellulose hydrolysis in dilute acid catalyzed systems. A novel kinetic model was also developed to describe release of hemicellulose oligomers and monomers, and
its predictions were compared to experimental results. When water was pushed through biomass, solubilization of hemicellulose, total mass, and lignin increased with flow rate inconsistent with predictions by traditional first order kinetic models. Michigan State University determined that available extruders had insufficient residence times for their Ammonia Fiber Explosion (AFEX) treatment, and a new redesigned batch AFEX unit was designed, built, and tested. This system appears to deliver expected hydrolysis results, based on past experience, although it is still in the early stages of testing. The students and a post doc were thoroughly trained in analytical methods so they can treat and analyze a very large number of samples. By pressure cooking in water at controlled pH, Purdue University seeks to form oligomers but not degradation products, with post processing to fermentable sugars. They defined optimal times of 15 minutes at 190C for pretreatment resulting in 74% of cellulose
hydrolyzed to glucose by 60 FPU cellulase per g cellulose at 50C for 96 hours. Purdue analyzed corn stover before and after pretreatment for the project and to support their research and measured protein content for untreated stover. Texas A&M University treated biomass with lime plus air at varying temperatures for times up to 16 weeks. An 8 week treatment using a lime loading of 0.2 g Ca(OH)2/g biomass at 45C reduced the lignin content to 8% of the biomass weight, which is sufficient to render the biomass very reactive. Enzyme loadings as low a 1 FPU/g biomass were very effective at hydrolyzing polysaccharides and increased 3-day yields by a factor of 4.5 compared to untreated biomass. The National Renewable Energy Laboratory (NREL) participated through Department of Energy funding. NREL acquired, analyzed, maintained, and supplied corn stover and cellulase enzyme. NREL also trained students on laboratory procedures, provided technical assistance, and fermented samples from each
participant. Process and economic models were developed and capital and operating costs projected for most of the pretreatments based on data and assumptions provided by appropriate researchers.
Impacts
Biomass provides a unique sustainable route to making organic fuels and chemicals, with very low greenhouse gas emissions being a particularly powerful attribute of cellulosic biomass conversion. Utilization of abundant and low cost domestic cellulosic biomass would also improve energy security, reduce trade deficits, and create rural employment, and processing of biomass residues provides a unique solution to waste disposal. The cost and availability of cellulosic biomass are attractive for competitive production of commodity chemicals and fuels such as ethanol, and the primary challenge is to reduce processing costs. Pretreatment is vital to preparing cellulosic biomass for biological conversion operations. This project is directed at developing comparable information on optimized leading pretreatments for production of sugars from low cost cellulosic biomass for fermentation or reaction to high volume commodity products that would open up major new agricultural
markets. The effort is performed through a Biomass Refining Consortium among leaders in biomass pretreatment, and particular attention is focused on developing accurate data for corn stover as a feedstock. An Agricultural and Industrial Advisory Board guides the project and helps disseminate results. Data and projected costs for all pretreatment systems are compared on a consistent basis and published and otherwise widely disseminated, and opportunities are sought to accelerate commercial applications. The project thus gives significant momentum to biomass processing in addition to important educational benefits.
Publications
- Dale, Bruce E.; Laureano-Perez, L. 2002. "Spectroscopic Characterization of Pretreated Corn Stover," 24th Symposium on Biotechnology for Fuels and Chemicals, Gatlinburg, Tennessee, April 29 (poster).
- Kim, Tae-Hyun; Sunwoo, C; and Lee, Y. Y. 2002. "Pretreatment of Corn Stover by Aqueous Ammonia," Bioresource Technology (submitted for publication).
- Kim, Tae-Hyun; Lee, Y.Y. 2002. "Fractionation of Corn Stover by a Two-Stage Percolation Process," 24th Symposium on Biotechnology for Fuels and Chemicals, Gatlinburg, Tennessee (poster).
- Liu, Chaogang; Wyman, Charles E. 2002. "Effect of Flowrate on the Dissolution of Hemicellulose, Lignin, and Total Mass for Pretreatment of Corn Stover in a Flowthrough Reactor," 24th Symposium on Biotechnology for Fuels and Chemicals, Gatlinburg, Tennessee (poster).
- Liu, Chaogang; Wyman, Charles E. 2002. "Comparison of Batch and Flowthrough Biomass Pretreatment Systems for Biological Production of Fuels and Chemicals," 12th European Biomass Conference and Exhibition, Amsterdam, The Netherlands, June 17-21 (poster and proceedings paper).
- Lloyd, Todd A.; Wyman, Charles E. 2002. "Application of a Depolymerization Model for Predicting Thermochemical Hemicellulose Hydrolysis," Applied Biochemistry and Biotechnology (Proceedings of the 24th Symposium on Biotechnology for Fuels and Chemicals) (presentation on April 28 and paper accepted for publication in 2003).
- Teymouri, Farzaneh; Dale, Bruce E. 2002. "Effects of Pretreatment on the Activity of Enzymes in Plants: Cellulase Enzymes and Ribulose Diphosphate Carboxylase," 24th Symposium on Biotechnology for Fuels and Chemicals, Gatlinburg, Tennessee, May 1 (presentation).
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Progress 10/01/00 to 09/30/01
Outputs
The project is on schedule. The team met with its Agricultural and Industrial Advisory Board twice, as targeted, to coordinate activities, review plans and progress, and obtain feedback. The research team also conducted frequent conference calls throughout the year. Auburn University is developing aqueous ammonia pretreatment by Ammonia Recycled Percolation (ARP). Auburn constructed a reactor system, and work was begun with corn stover. The composition and enzymatic digestibility of treated biomass were determined. Initial results show selective, efficient lignin removal while retaining most of carbohydrates, a widely adjustable delignification range, ability to make lignin-free, pulp-grade material, and highly digestible cellulose (above 90%). Dartmouth focused on determining times, temperatures, percent acid, and percent solids to maximize sugar yields for water-only and dilute acid batch systems. Literature data was assembled, and coupled heat transfer and kinetic
models and batch tube experiments were applied to devise heat-up strategies and provide performance data. The NREL steam gun was used to pretreat corn stover without acid addition. New analytical equipment was acquired to improve the accuracy of results. The Michigan State University team is emphasizing ammonia fiber explosion (FIBEX) research. A commercial extrusion device (Wenger, Inc. Sabetha, Kansas) was shown to be capable of performing ammonia treatment safely and reliably on fibrous biomass feedstocks without ammonia blowback. Data analysis indicates that the retention time in the extruder must be increased and that a positive pressure pump is required to meter the ammonia rather than relying on ammonia tank delivery pressure. Purdue University applies controlled pH pretreatment with a 2L stirred tank and steel tubes submersed in a sandbath. The 2L reactor treats larger quantities but has a 60 minute heat-up time before target temperatures are attained. The much smaller tubes
achieve shorter (1 to 3 minutes) heat-up times that better represent industrial conditions. Comparison of results will quantify the effect of heat-up time on pretreatment and support modeling and prediction of performance. Reactors were constructed at Texas A&M University for lime treatment at temperatures of 25, 35, 45, and 55oC. The 25oC reactor began operating, and the other reactors were tested. The 35oC reactor overheated, and a heat exchanger was being applied to correct this problem. Once all reactors are fully operational, pretreatment will be studied for months at each temperature. This data will be used to design "in pile" lime treatments to enhance biomass digestibility while in storage. The National Renewable Energy Laboratory (NREL) supported the project through Department of Energy funding. Economic models were developed with ASPEN simulation software for the pretreatment methods above integrated into an ethanol process. NREL also arranged a controlled supply of corn
stover for all team members, characterized and provided standard cellulase enzyme, and sponsored visits of five students from the participating institutions to NREL for training and coordination.
Impacts
Biomass offers the only sustainable resource for making organic fuels and chemicals, with perhaps the most powerful attribute of cellulosic biomass conversion being very low greenhouse gas emissions. Utilization of abundant and low cost domestic cellulosic biomass would also improve energy security, reduce trade deficits, and create rural employment. In addition, processing biomass residues provides a unique solution to waste disposal. Ethanol made from biomass can be blended with gasoline to improve octane and promote more complete combustion, while neat ethanol provides even greater air and water pollution benefits. Pretreatment is a vital step to cellulosic biomass utilization. This project focuses on developing comparable optimized information on leading pretreatments for production of sugars from low cost cellulosic biomass for fermentation or reaction to high volume commodity products that would open up major new agricultural markets. The effort is performed
through a Biomass Refining Consortium among leaders in biomass pretreatment. First priority is given to insuring accurate data for corn stover, but a hardwood and switchgrass are planned to be included later, as possible. An Agricultural and Industrial Advisory Board guides the project and helps disseminate results. Data for all pretreatment systems are compared on a consistent basis and published and otherwise widely disseminated, and opportunities are sought to accelerate commercial applications. The project thus gives significant momentum to biomass processing in addition to important educational benefits.
Publications
- No publications have been made at this early stage. However, initial results were presented at the 23rd Symposium on Biotechnology for Fuels and Chemicals held in Breckenridge, Colorado in May, 2001, and plans are underway to present and publish results in the next year.
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