Zirconium tripolyphosphate as an efficient catalyst for the hydrogenation of ethyl levulinate to γ-valerolactone with isopropanol as hydrogen donor

Hydrogenation of levulinic acid and its esters to produce γ-valerolactone (GVL) is an important reaction in the process of biomass valorization. Herein, a series of novel and porous acid–base bifunctional Zirconium tripolyphosphate were successfully synthesized and utilized to catalyze the hydrogenation of ethyl levulinate (EL) to GVL. It was found that Zr-TPPA-3 with a large number of Lewis acid–base sites and a high specific area displayed the highest catalytic activity, a satisfied GVL yield of 93.1% with 99.5% EL conversion was obtained under the optimal reaction conditions. In addition, poisoning experiments revealed that the acid–base sites play a synergistic effect in the hydrogenation of EL to GVL, and finally proposed a plausible reaction mechanism.