Conversion of biomass-derived ethyl levulinate into γ-valerolactonevia hydrogen transfer from supercritical ethanol over a ZrO2 catalyst

Abstract

A green and efficient process was developed for the conversion of biomass-derived ethyl levulinate (EL) into γ-valerolactone (GVL) using supercritical ethanol as the hydrogen donor and the reaction medium over low-cost and eco-friendly ZrO₂ catalysts, which were prepared by the precipitation method and characterized by BET, SEM, XRD, FT-IR, TGA-DTA, TPD-NH₃ and TPD-CO₂. The results indicated that amorphous ZrO₂ with a high specific surface area and a large number of acid–base sites exhibited the highest catalytic activity, an excellent GVL yield of 81.5% with 95.5% EL conversion was achieved at 523 K over 3 h. In addition, combined with the results of poisoning experiments, a plausible mechanism of catalytic transfer hydrogenation (CTH) via a six-membered ring transition state was also presented.