Sunday, May 3, 2009
3-60
Comparison of Kinetics of Xylose and Lignin Removal During Hot Water and Dilute-Acid Pretreatment of Corn Stover using a Continuous Flow-Through Reactor
Yun Ji1, Sridhar Viamajala2, Michael Selig3, Todd B. Vinzant3, and Melvin P. Tucker4. (1) Chemical Engineering, UND, 241 Centennial Drive, Grand Forks, ND 58202, (2) Biological and Irrigation Engineering, Utah State University, 4105 Old Main Hill, Logan, UT 84322-4105, (3) Chemical and Biosciences Center, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO 80401, (4) National Bioenergy Center, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO 80401
A flow through reactor (FTR) was used to determine the kinetics of xylose and lignin removal during hot water and dilute-acid pretreatment for bioethanol production. The removal rates of xylan and lignin during hot water (HW) and dilute-acid flow-through (DA) experiments with corn stover were studied between 170°C and 230°C for HW and 150°C and 210°C for DA. During all FTR pretreatments, insoluble dark precipitates were observed in the effluent and were characterized as lignin-carbohydrate complexes (LCC). Oligomeric and monomeric xylan was measured in the effluent during all of the FTR experiments. At temperatures beyond 200 °C significant xylan degradation to unknown products was observed. Total xylan removed was proportional to lignin and acetate release over the reaction time. Increases in pretreatment temperatures from 200°C to 230 °C did not significantly enhance the kinetics of xylan, lignin or acetate removal. Melting and mobilization of lignin also likely contribute to the process of xylan release. The results show that a flow through reactor is suitable for kinetics studies because the products are removed from the reaction zone, therefore less sugar degradation and lignin condensation reactions occur as compared to a batch reactor system.