Selective conversion of biomass-derived levulinic acid to ethyl levulinate catalyzed by metal organic framework (MOF)-supported polyoxometalates

Abstract The esterification of levulinic acid (LA) and ethanol into ethyl levulinate is an attractive biomass conversion process since the product EL has wide applications as food additive, fragrance and fuel. Herein, a metal-organic framework (MOF)-supported phosphomolybdic acid [Cu-BTC][HPM] was synthesized with 1,3,5-Benzenetricarboxylic acid, copper nitrate and phosphomolybdic acid in a one-step process at ambient temperature. The synthesized [Cu-BTC][HPM] was used for the catalytic esterification of levulinic acid to EL in ethanol, and showed excellent activity with a high EL yield close to 100% at 120 °C for 6 h, which should be ascribed to the uniform dispersion of HPM embedded in the MOF. The [Cu-BTC][HPM] catalyst could keep stable crystal structure and active component contents, and thus exhibited good stability in recycling process.