Synergetic effect of VOx and TeOx species in mesoporous SiO2 on selective oxidation of propane to acrolein

A mesoporous silica with incorporated vanadium (V) and tellurium (Te) (3%VTezOx-MS; z = 0–0.33), synthesized by an evaporation-induced self-assembly route, was used as a model catalyst to investigate the synergetic effect of VOx and TeOx species on propane oxidation to acrolein. It was found that V in the catalyst was predominantly present as a highly dispersed VO4 species, while Te existed as a highly dispersed TeOx species when the Te/V atomic ratio was below 0.2. Acrolein formation rate was positively correlated with TeOx content when both VOx and TeOx in the catalysts were in a highly dispersed state. Study of the propane oxidation pathways further indicated that highly dispersed VO4 in close contact with highly dispersed TeOx constituted the active sites for direct oxidation of propane to acrolein. These binary sites satisfied all the required functions for the reactions, including consecutive sequence of activation of propane and propylene intermediate followed by inserting oxygen into the as-formed allylic species.