Ethyl levulinate production from cellulose conversion in ethanol medium over high-efficiency heteropoly acids

Abstract

Cellulose conversion for ethyl levulinate (CCEL) production is a potential technology for obtaining liquid fuels. Combined the inherent characteristics of cellulose with “homogeneous reaction-heterogeneous separation” feature of heteropoly acids (HPAs), HPAs catalyzed CCEL under ethanol medium were investigated. Various characterizations confirmed HSiW had appropriate Brønsted and Lewis acid sites. Therefore, HSiW achieved the highest cellulose conversion (95.25 %) and ethyl levulinate (EL) yield (77.05 %), and EL selectivity reached to 75.15 % under optimized reaction conditions. Additionally, the reaction pathways of CCEL were proposed and the reactions of fructose dehydrated into hydroxymethylfurfural (HMF) and further alcoholysis into EL were improved by HPAs. The successfully established kinetic model of CCEL indicated the activation energies of cellulose conversion into HMF (26.90 kJ·mol−1) and HMF alcoholysis for EL (24.22 kJ·mol−1) were significantly lower than those of them transformed to humins (99.19 and 53.68 kJ·mol−1), suggesting HPAs catalysis could effectively inhibit humus generation.