Cation and vanadium substituted heteropolyacid catalysts for vapor phase oxidation

摘要

This invention relates to heteropolyacids characterized by their comprising phosphorus as the heteroatom and molybdenum and/or tungsten at octahedral sites, some of the molybdenum and/or tungsten having been replaced with vanadium and at least one transition metal or main group cation, the vanadium and cation occupying the octahedral sites surrounding the phosphorus heteroatom in the heteropolyacid structure. This invention also concerns the use of these heteropolyacids as catalysts in the oxidation of n-butane to maleic anhydride.