Supercritical carbon dioxide pretreatment of corn stover and switchgrass for lignocellulosic ethanol production

摘要

Supercritical CO_2 (SC-CO_2), a green solvent suitable for a mobile lignocellulosic biomass processor, was used to pretreat corn stover and switchgrass at various temperatures and pressures. The CO2 pressure was released as quickly as possible by opening a quick release valve during the pretreatment. The biomass was hydrolyzed after pretreatment using cellulase combined with β-glucosidase. The hydrolysate was analyzed for the amount of glucose released. Glucose yields from corn stover samples pretreated with SC-CO_2 were higher than the untreated sample's 12% glucose yield (12g/100g dry biomass) and the highest glucose yield of 30% was achieved with SC-CO_2 pretreatment at 3500psi and 150°C for 60min. The pretreatment method showed very limited improvement (14% vs. 12%) in glucose yield for switchgrass. X-ray diffraction results indicated no change in crystallinity of the SC-CO_2 treated corn stover when compared to the untreated, while SEM images showed an increase in surface area.