10-17: Pretreatment Kinetics of Switchgrass Hemicelluloses

Hemicelluloses account for 20 to 40% of biomass and are composed of sugars that can be used as substrates for conversion to valuable fuels and chemicals. However, the hydrolysis of hemicelluloses during pretreatments such as autohydrolysis and dilute acid hydrolysis produces xylo-oligomers and degradation products that inhibit hydrolytic enzymes and fermentation microorganisms. This work explored the decomposition kinetics of hemicelluloses, which were alkali-extracted from July- and February-harvested Alamo switchgrass, to better understand the formation of monomers, oligomers, and degradation products. Alkali-extracted hemicelluloses were subjected to pretreatments with sulfuric acid concentrations ranging from 0 to 1% (w/w) and temperatures ranging from 140 to 160 ^oC. While similar products resulted from both hemicelluloses, the concentrations and yields of monomers and degradation products differed between the July- and February-harvested samples. July hemicelluloses produced more glucose and hydroxymethylfurfural, and February hemicelluloses produced more formic acid. Results also demonstrated the effects that acid concentration and temperature exhibit on hydrolysis rates.