(511c) Production of Carbohydrates From Lignocellulosic Biomass for Catalytic and Biological Upgrading Using Gamma-Valerolactone As a Solvent

Efficient and economically viable depolymerization of the cellulose and hemicellulose fractions of biomass to produce soluble carbohydrates is a primary obstacle to the successful commercialization of biologically-based biofuel and bio-product production technologies. Biomass depolymerization using pretreatment and enzymatic hydrolysis, ionic liquids, or concentrated mineral acids are all successful approaches to producing carbohydrates at high yields. However, the life cycle and economic cost of the chemical or biochemical catalysts associated with these technologies constitute significant challenges to their implementations. We will show in this presentation that 80-90% yield of hemicellulose and 70-80% yield of cellulose can be recovered as soluble carbohydrates from lignocellulosic biomass by flowing a solution of gamma-valerolactone (GVL) (80-90 wt% GVL with water and 0.005 M H2SO4) through biomass at temperatures between 160-220ºC. GVL is an inexpensive solvent that can be derived from cellulose or hemicellulose, and the associated acid concentrations used in this method are 100 times lower than those typically used for biomass pretreatment. Reaction parameters can also be modified to target a combination of furfural at high concentrations (2-5 wt%) and C₆ carbohydrates in separate streams. Furthermore, the aqueous phase along with 50-90% of the sugars can be separated from GVL by various methods. With this separation, sugar concentrations increase by a factor of 10 – 40, thereby reaching 25 – 75 g/L. This aqueous stream of carbohydrates can be converted to ethanol using fermentation and to furans through catalytic dehydration in a biphasic system.