Enzymatic liquefaction of untreated corn stover
There is an ever increasing need for renewable alternatives to fossil fuels derived from petroleum. This makes feedstocks in the form of lignocellulosic biomass attractive substrates for the production of ethanol and value added chemicals. However, the economics of converting lignocellulosic materials involve high processing costs attributed with pretreatment of the biomass and the use of enzymes for saccharification. Corn stover was obtained for the examination of an upstream processing step to transform the material into a pumpable slurry for subsequent pretreatment and saccharification. Biomass liquefaction was carried out using the enzyme Depol 692L (Biocatalysts, Wales, UK) at 50°C with a mixing speed of 290 RPM using a dual-impeller design. Solids were added in a fed-batch manner over a course of 8 hours to reach a final solids concentration of 15% (w/v). Slurry viscosity was analyzed in real time to determine the flowability of the mixture. Minor changes to the particle size distribution were observed as liquefaction proceeded. A decrease in insoluble solids concentration was seen in liquefied corn stover versus the control, which could help explain the approximately 200 cP drop in viscosity over the control. When pretreatment (190°C for 15 min. at 10% and 15% solids) of liquefied material was carried out, an increase in glucose formation was seen over raw, pretreated corn stover. Total glucose formation after pretreatment andenzyme hydrolysis (50°C and 2.5 FPU per gram glucan of Cellic ® CTec3) was higher for liquefied material than raw material.
Ladisch, Purdue University.
Agricultural engineering|Chemical engineering
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