One-step upgrading of bio-based furfural to γ-valerolactone HfCl-mediated bifunctional catalysis.

γ-Valerolactone (GVL) is an attractive biomass-derived platform molecule that plays an important role in the production of biofuels and biopolymers. The synthesis of GVL from renewable biomass and its derivatives has great application prospects but also presents challenges due to the multiple conversion steps involved. Here, a HfCl-mediated acid-base bifunctional catalytic system was developed, which was demonstrated to be efficient for upgrading furfural (FF) to GVL in a single pot with unprecedented performance. The Lewis acidity of Hf and moderate basicity of HfO(OH)·HO, and strong Brønsted acidity of HCl generated from HfCl hydrolysis were found to play a synergistic role in the cascade reaction processes, mainly contributing to the pronounced catalytic activity. The effects of the key reaction parameters, such as the catalyst dosage, reaction time, and temperature, on GVL production were optimized by response surface methodology. It is worth mentioning that the recovered catalyst after thermal treatment could be directly used for the hydrogen transfer processes, like FF-to-furfuryl alcohol conversion. This catalytic strategy opens a new avenue for the selective conversion of biomass feedstocks involving multiple steps and complex processes.