Understanding pretreatment processes

FUEL 178

David K. Johnson, david_johnson@nrel.gov, Chemical and Biosciences Center, NREL, 1617 Cole Blvd, Golden, CO 80401 and Richard Elander, Richard_Elander@nrel.gov, National Bioenergy Center, National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, CO 80401.
Conversion of lignocellulosic biomass to sugars and ethanol requires an effective pretreatment before the cellulose can be efficiently hydrolyzed by enzymes. Pretreatment conditions cover the entire range from low to high pH, moderate to high temperatures, and minutes to weeks. As with all chemical processes, pretreatments are only successful if they generate the desired products in high yield and undesirable products are minimized. Development of tools to understand the effectiveness of pretreatment processes is an active area of research. Physico-chemical characterization of the lignocellulosic product can indicate pretreatment effectiveness. Characteristics typically tracked are cellulose crystallinity, accessibility and porosity. Microscopic imaging can also be used to follow changes in lignin and xylan distribution in the plant cell wall. Using these tools, we are attempting to gain a better understanding of how pretreatment processes can generate highly digestible cellulosic substrates so that biomass can converted to sugars with the highest possible yields.