Microwave-assisted condensation approach for vanadium silicate microspheres and their catalytic activity in cyclohexene epoxidation and ethyl lactate oxidation

Abstract

A novel, highly efficient condensation approach for the preparation of heterogeneous vanadium silicate microspherical catalyst is introduced. This synthetic method is based on a microwave-assisted preparation of hybrid vanadium biphenyl dicarboxylate-based precursor solution and subsequent condensation with (3-aminopropyl)triethoxysilane. The as-prepared hybrid metallosilicate is then calcined at 500 °C to obtain amorphous and porous vanadium silicate microspheres with highly dispersed vanadium species inserted into the silicate matrix. This catalyst with 2.85 wt% of vanadium contains evenly distributed VOx species, which possesses high catalytic activity in a cyclohexene epoxidation reaction, reaching a conversion of 54 % after 4 h with 92 % selectivity to cyclohexene oxide. The catalyst's TOF value achieved 220 h−1, indicating its high performance compared to vanadium-containing catalyst analogs. Furthermore, a significant catalytic activity of prepared vanadium silicate microspheres in ethyl lactate oxidation to ethyl pyruvate with the conversion of 21 % at mild conditions shows a high potential of the catalyst for industrial application compared to the contemporary V2O5 heterogeneous catalyst.