Abstract: Catalyst activity is substantially increased in phosphorus-vanadium-oxygen catalysts for the preparation of maleic anhydride from saturated hydrocarbons having 4 to 10 carbon atoms by the addition of boron to the catalyst composition.

Abstract: The process for the conversion of saturated hydrocarbons having from 4 to 10 carbon atoms to maleic anhydride is enhanced when a mixture of oxygen and saturated hydrocarbon is contacted with catalysts comprising phosphorus, vanadium, oxygen and an element selected from the group consisting of titanium, silicon, or mixtures of these elements. The process is particularly useful for the conversion of butane to maleic anhydride.

Abstract: The performance of phosphorus-vanadium-oxygen catalysts useful for the conversion of saturated aliphatic hydrocarbons to maleic anhydride is dependent on the controlled calcination of the catalyst precursor. Phosphorus-vanadium-oxygen catalysts are prepared by mixing phosphorus and vanadium compounds to form precursors containing tetravalent vanadium, and calcining the precursors in an oxidizing atmosphere until a controlled level of pentavalent vanadium has been achieved, and then calcining the precursors in an inert atmosphere to higher temperatures to provide catalysts with the desired oxidation levels that are promptly active, so that valuable manufacturing facilities are not required to "activate the catalyst.