Use of improved mixed vanadium phosphorus oxide catalyst in oxidation processes

Claim 1

A process for the production of maleic anhydride by the oxidation of 4 carbon atom hydrocarbons with molecular oxygen or an oxygen containing gas in the vapor phase at a reaction temperature of about 250° C. to about 600° C. in the presence of a catalyst containing the mixed oxides of vanadium and phosphorus, wherein said catalyst is prepared by (a) introducing a pentavalent vanadium compound into an organic liquid reaction medium selected from alcohols and glycols capable of reducing at least a portion of the vanadium to a valence state of about +4 in the absence of corrosive reducing agents; (b) introducing at least one pentavalent phosphorus compound into the reaction medium; (c) effecting reduction of the vanadium prior or subsequent to the addition of the phosphorus compound and reacting the vanadium with the phosphorus compound to form a catalyst precursor, (d) removing from the reaction medium at least 1.5 moles of the organic liquid including organic oxidation byproducts per mole of vanadium reduced or reacted during the reduction or reaction; (e) recovering the catalyst precursor from the reaction medium; (f) drying the catalyst precursor; and (g) calcining the catalyst precursor.