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: 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 calcining the catalyst precursor at 325.degree.-375.degree. C. in the presence of oxygen and a saturated aliphatic hydrocarbon.

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. By the process of the present invention, a new phosphorus-vanadium-oxygen composition is formed which is converted to the precursor. Catalysts formed by the process of the present invention, when used for the conversion of saturated hydrocarbons to maleic anhydride, provide higher yields of maleic anhydride.

Abstract: In a method for preparing a phosphorus-vanadium-oxygen catalyst wherein a pentavalent vanadium compound and a trivalent phosphorus compound are brought together in a liquid reaction zone under conditions to provide a substantial amount of tetravalent vanadium and to form a phosphorus-vanadium-oxygen catalyst precursor having a phosphorus to vanadium atom ratio between about 0.9:1 and about 2:1, the improvement of this invention comprises adding a sufficient amount of a surfactant to the liquid reaction zone to form a dispersion which comprises a liquid, the surfactant and a dispersoid of the phosphorus-vanadium-oxygen catalyst precursor.

Abstract: In a method for preparing a phosphorus-vanadium-oxygen catalyst wherein a pentavalent vanadium compound and a trivalent phosphorus compound are brought together in a liquid reaction zone under conditions to provide a substantial amount of tetravalent vanadium and to form a phosphorus-vanadium-oxygen catalyst precursor having a phosphorus to vanadium atom ratio between about 0.9:1 and about 2:1, the improvement of this invention comprises adding a sufficient amount of a surfactant to the liquid reaction zone to form a dispersion which comprises a liquid, the surfactant and a dispersoid of the phosphorus-vanadium-oxygen catalyst precursor.

Abstract: The productivity of phosphorus-vanadium-oxygen catalysts useful for converting saturated hydrocarbons containing from 4 to 10 carbon atoms to maleic anhydride can be increased by the order of preparatory steps used to prepare such catalysts. Phosphorus-vanadium-oxygen catalysts are prepared by mixing phosphorus and vanadium compounds to form precursors, shaping precursors and then calcining the precursors to form the catalysts. The catalysts are particularly beneficial for the conversion of butane to maleic anhydride.

Abstract: The prior art discloses that phosphorus-vanadium-oxygen catalysts wherein the phosphorus to vanadium atom ratio is between about 1:2 and about 2:1, and wherein at least about 20 atom percent of the vanadium is in the tetravalent state, are useful for the conversion of aliphatic hydrocarbons to maleic anhydride. It has now been found that when the pore volume of the catalysts from pores having diameters between about 0.8 micron and about 10 microns is greater than 0.02 cc/g, the catalyst is particularly useful for the conversion of saturated hydrocarbons, such as butane, to maleic anhydride.