Kinetics of xylose reversion reactions during acid pretreatment

FUEL 179

Mark R. Nimlos, mark_nimlos@nrel.gov1, Heidi M. Pilath, Heidi_Pilath@nrel.gov1, David K. Johnson, David_Johnson@nrel.gov2, Xianghong Qian, xhqian@engr.colostate.edu3, Haitao Dong, xhqian@engr.colostate.edu3, and Michael E. Himmel, mike_himmel@nrel.gov1. (1) National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, CO 80401, (2) National Bioenergy Center, National Renewable Energy Laboratory, 1617 Cole Blvd, Golden, CO 80401, (3) Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523-1374
Acid pretreatment of biomass is commonly used to disassemble hemicellulose into suugars and expose cellulose microfibrils for further hydrolysis, usually using enzymes. Economics dictate that the yield of sugars formed during pretreatment remain high. Therefore, it is advantageous to optimize the hydration of hemicellulose to form sugars while minimizing the sugar destruction reactions. In order to achieve this optimization, it is desirable to know the kinetics for these processes. In this study, we have measured the kinetics of loss of xylose by reversion reactions. The kinetics of these reactions have been measured using a microwave heated reactor. Reactant and product concentrations have been measured using HPLC. Rate constants have been extracted and the apparent temperature dependence has been used to determine reaction free energies and energy barriers. The experimental kinetics and energetics have been compared to results obtained using quantum mechanical modeling.
 

Clean Energy, Fuels and Chemicals from Biomass
9:00 AM-11:45 AM, Wednesday, April 9, 2008 Morial Convention Center -- Rm. 242, Oral

Sci-Mix
8:00 PM-10:00 PM, Monday, April 7, 2008 Morial Convention Center -- Hall A, Sci-Mix

Division of Fuel Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008