Abstract: An oxidation catalyst comprising vanadium, phosphorus, and oxygen having average vanadium valence less than about 4.10, and a method of preparing such catalyst, is provided. The catalyst has side crush strength of at least about 5 lbs. and improved yield of maleic anhydride from n-butane between about 1% and about 6% absolute. The catalyst is formed by exposing a conventional active VPO catalyst having average vanadium valence between about 4.10 and about 4.40 to an organic solvent having a dielectric constant between about 5 and about 55 under conditions that facilitate an oxidation-reduction reaction, reducing the valence of the vanadium below 4.10.

Abstract: Disclosed is an improved process for the epoxidation of ethylene, wherein ethylene is reacted with oxygen in a mol ratio of about one, in the presence of a silver metal catalyst and a halide gas phase inhibitor, at a pressure of about 200 to 300 psig, said improvements comprising: introducing into the reaction zone a feed gas mixture comprising:30 to 90 mol % ethylene,0 to 55 mol % methane,0 to 15 mol % one or more inert, non-hydrocarbon gases or mixtures thereof,0 to 10 mol % carbon dioxide,2 to 10 mol % oxygen,1 to 50 ppm organic halide gas phase inhibitor, and maintaining the temperature in the reaction zone between 180.degree. and 350.degree. C.