One-pot chemocatalytic transformation of cellulose to ethanol over Ru-WOx/HZSM-5

Abstract

Chemocatalytic production of bioethanol from cellulosic biomass is significant for both low-carbon energy development and greenhouse gas control. In this work, a multifunctional Ru-WO_x/HZSM-5 catalyst was designed and prepared for the one-pot efficient transformation of cellulose and raw biomass (bagasse and corn stalk) to bioethanol via a series of cascade reactions. Addition of Ru/WO_x, which could promote the retro-aldol condensation reaction but not oligomerization, led to a 87.5% yield of ethanol from 1 wt% cellulose under mild conditions (235 °C, 3 MPa H₂, in water). Further combining a two-stage heating strategy for high concentration feedstock conversion achieved a 53.7% yield of ethanol from 5 wt% cellulose. Characterization studies revealed a highly dispersed Ru₃W₁₇ alloy along with moderate acid sites that displayed a synergistic catalytic effect. The catalytic system can be regulated to promote hydrolysis, retro-aldol condensation, dehydration and hydrogenation to achieve ethanol and suppress side reactions such as oligomerization to form humins.