Molybdenum oxide-based systems, prepared starting from Anderson-type polyoxometalates precursors, as catalysts for the oxidation of i-C_4 hydrocarbons

摘要

Te/Mo and V/Te/Mo mixed oxides, prepared starting from Anderson-type polyoxometalates precursors, were characterized and used as catalysts for the oxidation of isobutene and of isobutane to methacrolein. Catalysts were active and moderately selective in olefin oxidation; the addition of V slightly increased the activity, but led to a worsening of the selectivity to methacrolein. The dispersion over high-surface-area silica improved the activity, due to the higher number of active sites available, and to the generation of more reducible species, but worsened the selectivity to methacrolein. Diffusional effects were likely responsible for the enhanced degree of combustion. Catalysts were instead non-active in the oxidation of isobutane.