Abstract: Phosphorus-vanadium mixed oxide oxidation catalysts are prepared by introducing a substantially pentavalent vanadium-containing compound and a pentavalent phosphorus-containing compound into an alcohol medium capable of reducing the vanadium to a valence state less than +5 in the presence of an alcohol-modifying agent to form a phosphorus-vanadium mixed oxide catalyst precursor. The catalyst precursor is recovered, dried, formed into desired structures, and calcined at temperatures from about 250.degree. C. to about 600.degree. C. The catalysts are highly effective in that they exhibit a weight/weight productivity of at least 70 grams of maleic anhydride per kilogram of catalyst per hour.

Abstract: Maleic anhydride is produced by the oxidation of a non-aromatic hydrocarbon having at least four carbon atoms in a straight chain with molecular oxygen or a molecular oxygen-containing gas in the vapor phase in the presence of a phosphorus-vanadium mixed oxide oxidation catalyst. Such catalysts are prepared by introducing a substantially pentavalent vanadium-containing compound and a pentavalent phosphorus-containing compound into an alcohol medium capable of reducing the vanadium to a valence state less than +5 in the presence of an alcohol-modifying agent to form a phosphorus-vanadium mixed oxide catalyst precursor. The catalyst precursor is recovered, dried, formed into desired structures, and calcined at temperatures from about 250.degree. C. to about 600.degree. C. The catalysts are highly effective in that they exhibit a weight/weight productivity of at least 70 grams of maleic anhydride per kilogram of catalyst per hour.

Abstract: Catalysts useful for the partial oxidation of non-aromatic hydrocarbons, particularly n-butane, with molecular oxygen or a molecular oxygen-containing gas in the vapor phase to produce maleic anhydride are provided which comprise mixed oxides of phosphorus and vanadium. The catalysts are highly effective in that they exhibit a weight/weight productivity of at least 70 grams of maleic anhydride per kilogram of catalyst per hour.

Abstract: Phosphorus-vanadium mixed oxide catalysts are prepared by contacting a tetravalent vanadium compound, dissolved in an aqueous, non-oxidizing acid medium, with crystalline diphosphoric acid to form a phosphorus-vanadium mixed oxide catalyst precursor. The resulting catalyst precursor-containing solution is subjected to a series of concentration/dilution cycles to induce crystallization of the catalyst precursor. The crystals are collected, dried, formed into desired structures, and calcined at temperatures from about 300.degree. C. to about 600.degree. C.

Abstract: Maleic anhydride is produced by the oxidation of a nonaromatic hydrocarbon having at least four carbon atoms in a straight chain with molecular oxygen or a molecular oxygen-containing gas in the vapor phase in the presence of a phosphorus-vanadium mixed oxide catalyst. Such catalysts are prepared by contacting a tetravalent vanadium compound, dissolved in an aqueous, non-oxidizing acid medium, with crystalline diphosphoric acid to form a phosphorus-vanadium mixed oxide catalyst precursor. The resulting catalyst precursor-containing solution is subjected to a series of concentration/dilution cycles to induce crystallization of the catalyst precursor. The crystals are collected, dried, formed into desired structures, and calcined at temperatures from about 300.degree. C. to about 600.degree. C.

Abstract: Process for the manufacture of maleic anhydride which comprises contacting in the vapor phase a mixture of butane and molecular oxygen with a catalyst comprising in chemical combination phosphorus, vanadium, oxygen and a catalyst modifier comprising titanium combined with one or more elements selected from the group consisting of aluminum, cerium, cobalt and iron.

Abstract: In conventional procedures for the preparation of phosphorus-vanadium-oxygen catalysts, with or without promoting elements or carriers, the phosphorus compounds and vanadium compounds are mixed under conditions to form precursors. These precursors are then heated to temperatures up to 600.degree. C. to form phosphorus-vanadium-oxygen catalysts suitable for the conversion of saturated hydrocarbons, such as butane, to maleic anhydride. The present invention employs a new phosphorus-vanadium-oxygen hydrogen intermediate composition which can be converted to the precursor. Catalysts formed from the intermediate are used, according to this invention, for the conversion of saturated hydrocarbons to maleic anhydride.

Abstract: An improvement in a method of preparing catalysts for the manufacture of maleic anhydride by oxidizing a saturated hydrocarbon. The catalyst is prepared by a process in which a catalyst precursor, containing tetravalent vanadium, is formed into agglomerates and calcined, the improvement being quick freezing the catalyst precursor before calcining.