(127a) Production and Upgrading of Sugars From Biomass

Lignocellulosic biomass is a renewable feedstock for production of fuels and chemicals. We will show in this presentation that gamma-valerolactone (GVL) can be used a solvent to convert the cellulosic fraction of lignocellulosic biomass into levulinic acid, while at the same conditions the hemicellulose fraction can be converted into furfural. This integrated processing strategy allows for the conversion of hemicellulose and cellulose simultaneously in a single reactor, thus eliminating pre-treatment steps to fractionate biomass and simplifying product separation.  More generally, because of the versatility of sugars as chemical and biological intermediates, depolymerization of plant cellulose and hemicellulose to recover glucose and xylose is an integral part of biomass conversion processes. Current approaches are challenged by low yields of sugars and/or by high costs, such as the use of concentrated mineral acids, the use of enzymatic hydrolysis, or the use of ionic liquids.  We will also show in this presentation that GVL can be employed in a single step with 10-20 wt% water and dilute acid (5 mM H₂SO₄) to recover soluble carbohydrates more effectively than using classical solvents, such as water or water-ethanol mixtures with similar acid contents. Furthermore, we will show that the aqueous phase and the soluble sugars can be separated from GVL by various methods, thereby increasing the sugar concentration by a factor of 10 – 40, such that the final sugar concentration in the aqueous phase is from 25 – 70 g/L.  We show that this aqueous stream of carbohydrates is suitable for biological upgrading by microorganisms and for chemical transformation to furans. We suggest that this strategy could become a viable alternative to current recovery approaches employed for production of carbohydrates from lignocellulosic biomass, and spur further research in new solvent systems for improved biomass deconstruction.