3-45: Simultaneous Isomerization and Reactive Extraction of Biomass Sugars for Efficient Furan Production via High Yield Ketose Intermediate

Current methods for producing furans (hydroxy-methyl furfural (HMF) and furfural) from lignocellulosic biomass are limited in the efficiency of furan production due to incomplete conversion of the reactant sugars as well as undesired byproduct and humin formation. Hydrogenation products of these furans, such as dimethylfuran and dimethyltetrahydrofuran, are suggested as “drop-in” liquid transportation fuels. Conversion of biomass sugars with high yields to their ketose forms can immensely facilitate one-pot synthesis of furans from these sugars. Aldose-to-ketose isomerization, however, has a very unfavorable equilibrium, and high yield conversion to ketoses in a manner that allows for further conversion economically has yet to be demonstrated. We developed a novel simultaneous isomerization and reactive-extraction (SIRE) – followed by back-extraction (BE) – strategy that produces high yield, high concentration ketose sugars (in pure form) from biomass hydrolysate without significant energy inputs. In initial exploratory experiments with a pure xylose solution, SIRE-BE resulted in a nearly-pure (97%) xylulose stream concentrated 5-fold and at high yield – results which can be significantly improved by the process optimization. Our technology allows for the direct back-extraction of ketoses into acid-containing, benign reaction media; such media are ideal for high yield conversion of ketoses to furans under facile conditions. We report on high-yield, high-selectivity conversion of back-extracted xylulose to furfural through homogeneous synthesis under relatively low temperature conditions with minimal side-product formation. Results for one- and two-phase reaction systems will be presented.