Catalysis Today, Vol.304, 64-71, 2018
Surfactant templated synthesis of porous VOx-ZrO2 catalysts for ethanol conversion to acetaldehyde
Synthesis of VOx-ZrO2 catalysts with hierarchical porosity is reported here for first time. Surface areas of prepared materials reached values up to 211 m(2)/g with the intrinsic porosity on the border between micro-and mesopores. Physico-chemical properties and catalytic activity in ethanol oxidative dehydrogenation to acetaldehyde of these materials are compared with VOx/ZrO2 catalyst obtained by vanadia deposition on the surface of the already synthesized zirconia support with the hierarchical micro-meso-macroporosity with macrochannels of 200-500 nm in size. The VOx-ZrO2 sample prepared by deposition of vanadium on hierarchical zirconia exhibits high catalytic activity (TOF = 106.9 h(-1) at 200 degrees C), and especially high selectivity towards acetaldehyde. Acetaldehyde selectivity under reaction conditions varied between 99 and 92%. Directly synthesized VOx-ZrO2 catalysts showed higher selectivity to acetaldehyde compared to VOx-ZrO2 catalyst obtained by vanadia deposition on the surface of the already synthesized zirconia, but significantly lower activity probably due to incorporation of vanadium during the synthesis inside the channel walls where vanadium is not accessible to the gas molecules.