Synthesis and Characterization of Zirconia Supported Silicotungstic Acid for Ethyl Levulinate Production

A Keggin silicotungstic acid (HPS) catalyst was heterogenized by loading (10-40 wt %) over zirconia support, and the resulting catalysts were named ESZN-1 (10 wt %), ESZN-2 (20 wt %), ESZN-3 (30 wt %), and ESZN-4 (40 wt %). After that, synthesized catalysts were characterized using several tools and techniques which revealed that the Keggin structure of the parent HPS catalyst remained intact after heterogenization. Eventually, synthesized catalyst performance evaluation tests were performed for the production of ethyl levulinate from biomass-derived levulinic acid under microwave heating irradiations. Under optimum operating conditions, more than 90% LA conversion with 100% EL selectivity was obtained at a 110 degrees C temperature in 30 min in the presence of 100 mg of ESZN-4 in a solution containing levulinic acid and ethanol in a 1:43 ratio. A kinetic study on LA conversion in the presence of the ESZN-4 catalyst revealed a pseudo-first-order mechanism for ethyl levulinate synthesis.