Activity difference between the surfaces of micropore and the external of a vanadyl pyrophosphate catalyst for the selective oxidation of n-butane

摘要

Vanadyl pyrophosphate catalysts were prepared by activating the vanadyl hydrogen phosphate hemihydrate precursor in a F(N2) or a F(He) stream. The precursor was prepared by reducing vanadyl phosphate dihydrate with an alcohol. It was revealed that the catalysts involved micropores. Selectivity to maleic anhydride (MA), and external, micropore and BET surface areas depended on the alcoholes and the streams used. The rates of butane consumption and MA formation per unit external surface area or per unit micropore surface area were obtained from the relationship between the velocities per unit BET area, and the ratio of the micropore surface area to the BET area. It was revealed that the micropore surface was more active for the complete combustion than the external surface. As a result, the micropore surface increased the conversion of butane but decreased the MA selectivity because of the complete combustion.