Catalysts for preparation of aromatic carboxylic anhydrides

A process for the preparation of an aromatic carboxylic anhydride comprising reacting an aromatic hydrocarbon selected from the group consisting of alkyl substituted and unsubstituted aromatic hydrocarbons wherein the alkyl has 1 to 10 carbon atoms and the aromatic hydrocarbon has 6 to 14 carbon atoms, with a molecular oxygen-containing gas in the vapor phase in a reaction zone, in the presence of a solid oxidation catalyst, said solid oxidations catalyst being obtained by the steps of:

• (a) forming a catalyst precursor by depositing on titanium dioxide in the anatase form, a continuous monolayer amount of at least one zirconium oxide source which is convertible to zirconium dioxide, upon calcining;
• (b) calcining said catalyst precursor under conditions sufficient to convert at least a portion of said zirconium source into zirconium dioxide;
• (c) depositing upon the calcined catalyst precursor a catalytically effective amount of a vanadium source which is convertible to vanadium oxide upon calcining;
• and
• (d) calcining the catalyst solids formed in step (c) under conditions sufficient to convert at least a portion of said vanadium compound to vanadium oxide said catalyst containing from about 0.7 to 50 wt. % of vanadium oxides, calculated as V.sub.2 O.sub.5 and the mole ratio of vanadium to zirconium is about 0.1:1 to 20,000:1.