A porous inorganic zirconyl pyrophosphate as an efficient catalyst for the catalytic transfer hydrogenation of ethyl levulinate to γ-valerolactone

Catalytic transfer hydrogenation (CTH) of ethyl levulinate (EL) to gamma-valerolactone (GVL) is an alluring reaction in the field of biomass catalytic conversion, but it normally depends on the consumption of H-2. In this study, we report a porous Zr-containing inorganic pyrophosphate catalyst (ZrOPP), which was used as a catalyst for CTH of EL to GVL in the presence of isopropanol and characterized using FT-IR, py-FTIR, TGA, XRD, BET, XPS, ICP-AES, SEM, TEM, NH3-TPD, and CO2-TPD. We achieved a high yield of 94% GVL at 433 K for 11 hr. Furthermore, the ZrOPP has the trait of easy separation and could be reused more than five times without distinct decrease in activity and selectivity. In addition, this catalyst could also be applied to other catalytic hydrogenation reactions, such as those of cyclohexanone, acetophenone, 2-heptanone etc. Its outstanding performance was mainly ascribed to the acid sites from the Zr element and basic sites from phosphate groups interspersing on the surface of the catalyst.