Abstract: A process for the manufacture of a phosphorus/vanadium/metal oxide catalyst suitable for the oxidation of butane to maleic anhydride can be prepared by reacting orthophosphoric acid in an aliphatic alcohol and reacting a vanadium compound with an acid and the metal in the aliphatic alcohol to produce the phosphorus/vanadium/metal oxide catalyst.

Abstract: A process for the manufacture of a phosphorus/vanadium/metal oxide catalyst suitable for the oxidation of butane to maleic anhydride can be prepared by reacting in an aqueous medium a vanadium compound, inorganic acid and metal oxide, then adding orthophosphoric acid to form a soluble vanadium phosphorus metal oxide catalyst, removing the acidified water and adding an aliphatic alcohol, removing the alcohol and recovering under vacuum the solid phosphorus vanadium metal oxide catalyst.

Abstract: A process for reactivating a vanadium-containing oxidation catalyst, wherein the catalyst is treated first at from 100.degree. to 600.degree. C., with a volatile phosphorus compound in the presence of an oxygen-containing gas, and then at from 50.degree. to 600.degree. C. with sulfur trioxide or a mixture of a volatile sulfur compound and an oxygen-containing gas.

Abstract: The present invention provides a method for the preparation of oxidation catalysts containing mixed oxides of vanadium and phosphorus, which catalysts are particularly effective in the oxidation of n-butane, n-butenes, 1,3-butadiene or a mixture thereof with molecular oxygen or an oxygen-containing gas in the vapor phase to produce high yields of maleic anhydride with good selectivity. Vanadium phosphorus mixed oxide catalyst precursors prepared in solution in organic media are extracted from the organic media with water, with subsequent drying down to recover a precursor solid, or impregnation of a support with the aqueous solution.

Abstract: In the method for the preparation of maleic anhydride by oxidizing an aliphatic hydrocarbon in the presence of a phosphorus-vanadium-oxygen complex catalyst, the improvement which comprises employing a catalyst with enhanced crush strength.

Abstract: A novel catalyst for the oxidation of butane to produce maleic anhydride comprising a phosphorus and vanadium mixed oxide wherein the catalyst is prepared by using an organic medium and has a specific phase identified by characteristic X-ray pattern. A process for the manufacture of maleic anhydride from butane feedstock utilizing the novel catalyst.

Abstract: Vanadium phosphorus mixed oxide containing catalysts are prepared in an organic liquid reaction medium with heating wherein at least 1.5 moles organic liquid are removed from the reaction medium such as by distillation for each mole of vanadium which is reduced or reacted during such reaction and/or reduction. The resulting catalysts are useful for the production of maleic anhydride from 4 carbon atom hydrocarbons.

Abstract: Maleic anhydride is produced by oxidizing a straight chain C.sub.4 hydrocarbon with oxygen in a stream comprising 25 to 60% by volume of the C.sub.4 hydrocarbon, 20 to 45% by volume of oxygen and optionally inert gases to produce a stream containing at least 21/2% by volume of maleic anhydride and condensing maleic anhydride substantially free from water from this stream.

Abstract: A process is provided for the preparation of fluid bed oxidation catalysts containing the mixed oxides of vanadium and phosphorus, comprising the steps of preparing the catalyst precursor, comminuting the precursor, introducing the precursor into water to form an aqueous slurry and spray drying the slurry. The resulting microspheroidal particles are excellent fluid bed catalysts for the preparation of maleic anhydride from 4-carbon atom hydrocarbons.

Abstract: The present invention provides improved oxidation catalysts containing mixed oxides of vanadium and phosphorus and the method for the preparation thereof, which catalysts are particularly effective in the oxidation of n-butane, n-butenes, 1,3-butadiene or a mixture thereof with molecular oxygen or an oxygen-containing gas in the vapor phase to produce excellent yields of maleic anhydride with very good selectivity. At least one vanadium compound, a substantial portion of which is in the pentavalent state, and at least one phosphorus-containing compound is added to an organic liquid medium capable of reducing at least a portion of the vanadium to a +4 valence state, to form a reaction mixture. Partial reduction of the vanadium is effected in the presence of the phosphorus-containing compound and a highly ordered and uniform mixed vanadium phosphorus oxide-containing catalyst precursor is formed.

Abstract: Process for production of maleic anhydride comprising contacting n-butane-rich feed consisting essentially of n-butane, molecular oxygen and ballast gas with oxidation catalyst in a heat transfer medium-cooled, tubular reaction zone in which catalyst is graded in terms of reactivity such that reactivity increases to compensate for decreased reactant concentrations; removing effluent from the reaction zone; recovering maleic anhydride from the effluent; and recycling a major portion of the remaining effluent to the reaction zone.

Abstract: Catalysts particularly effective in the oxidation of n-butane, n-butenes, 1,3 butadiene and mixtures thereof with molecular oxygen or an oxygen-containing gas in the vapor phase to produce maleic anhydride are provided which comprise an essentially inert, at least partially porous support to which is adhered on its outer surface, catalytically active mixed oxides of vanadium and phosphorus or of vanadium, phosphorus and uranium in an amount greater than 50% to about 80% by weight of the combined support and active oxide.

Abstract: The present invention provides improved oxidation catalysts containing mixed oxides of vanadium and phosphorus and the method for the preparation thereof, which catalysts are particularly effective in the oxidation of n-butane, n-butenes, 1,3-butadiene or a mixture thereof with molecular oxygen or an oxygen-containing gas in the vapor phase to produce excellent yields of maleic anhydride with very good selectivity. At least one vanadium compound, a substantial portion of which is in the pentavalent state, and at least one phosphorus-containing compound is added to an organic liquid medium capable of reducing at least a portion of the vanadium to a +4 valence state, to form a reaction mixture. Partial reduction of the vanadium is effected in the presence of the phosphorus-containing compound and a highly ordered and uniform mixed vanadium phosphorus oxide-containing catalyst precursor is formed.