Sunday, May 3, 2009
3-101
A Comparison of Batch Tube and Microwave Reactors for Water-Only and Dilute Acid Pretreatment of Corn Stover
Jian Shi, Center for Environmental Research and Technology Department of Chemical and Environmental Engineering Bourns College of Engineer, University of California at Riverside, 1084 Columbia Avenue, Riverside, CA 92507, Yunqiao Pu, Institute of Paper Science and Technology, Georgia Institute of Technology, 500 10th Street, NW, Atlanta, GA 30332, Bin Yang, Center for Environmental Research and Technology, Bourns College of Engineering, University of California, Riverside, 1084 Columbia Avenue, Riverside, CA 92521, Arthur J. Ragauskas, School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30332, and Charles E. Wyman, Center for Environmental Research and Technology and Chemical and Environmental Engineering Department, University of California, Riverside, 1084 Columbia Avenue, Riverside, CA 92521.
Pretreatment is one of the most expensive steps in biological conversion of cellulosic biomass. Advanced pretreatment technologies are needed to significantly reduce costs, improve cellulose digestibility, simplify upstream and downstream operations, and provide revenues from co-products. The ability to target advances in this area has been slowed by limited understanding of pretreatment fundamentals and its effect on other processing operations, while more obvious cost reductions have already been realized. Better knowledge of pretreatment would also accelerate commercial applications by giving practitioners and financial organizations greater confidence in scale-up. Use of microwave heating could address a major challenge in pretreatment research of rapid and uniform heat up of biomass. Thus, we applied conventional batch tubes and microwave reactors to water-only and dilute acid pretreatment of corn stover to develop comparative data on sugar, lignin, and overall mass recovery profiles at identical conditions and found that overall sugar yields from microwave pretreatment were comparable to those from conventional sand bath systems. Solid state CP/MAS NMR and solution NMR were employed to elucidate biomass structural characteristics (i.e. cellulose and lignin) of pretreated corn stover, and the impact of pretreatment reactor choice on sugar recovery from enzymatic hydrolysis was determined. Microwave pretreatment demonstrated faster and more effective alteration of cellulose structural features compared to conventional sand batch pretreatment. This data was used to suggest new mechanisms that explain the different results for batch tube and microwave systems on a consistent basis to aid in applications and advances in pretreatment technology.