Catalyst for the production of maleic anhydride by the oxidation of butane

Claim 1

A catalyst for the production of maleic anhydride by the oxidation of butane which consists essentially of a phosphorus-vanadium mixed oxide with zinc as the promoter, wherein vanadium pentoxide in the presence of zinc is reduced and subsequently the vanadium zinc oxide solution is reacted with phosphoric acid, the atomic ratio of vanadium to phosphorus being in the range of 0.5:1 to 1.25:1 and the total atomic ratio of zinc to vanadium being in the range of 0.01:1 to 0.25:1 wherein the catalyst in the initial phase has a characteristic initial powder X-ray diffraction pattern using copper K alpha radiation as follows: ______________________________________ Line Position d angstrom 2.θ degrees Intensity ______________________________________ 5.7 15.6 100 4.5 19.7 41 3.7 24.3 25 3.3 27.1 32 3.1 28.8 14 2.9 30.5 40 2.8 32.2 9 2.7 33.7 20 ______________________________________ which upon heating at a temperature of about 600° to 800° F. under reaction conditions for the oxidation of butane to maleic anhydride converts to a phase having a characteristic powder X-ray diffraction pattern using copper K alpha radiation as follows: ______________________________________ Line Position d angstrom 2.θ degrees Intensity ______________________________________ 6.3 14.2 10 4.8 18.5 7 3.9 23.0 100 3.1 28.5 58 3.0 30.0 29 2.7 33.8 7 ______________________________________