Abstract: A process is provided for preparing fluid bed catalysts containing the mixed oxides of vanadium and phosphorus prepared from a mixed phosphoric acid source. A pentavalent vanadium compound is introduced into an organic liquid capable of reducing the vanadium, the vanadium is contacted with the mixed phosphoric acid source, the resulting catalyst precursor is comminuted, introduced into water to form an aqueous slurry and spray dried to form microspheroidal, fluidizable particles.

Abstract: The present invention provides a process 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. A vanadium compound is introduced into a liquid medium, a mixed phosphorus component comprising orthophosphoric acid and pyrophosphoric acid is added to the liquid medium, reduction of at least a portion of the vanadium to a +4 valence state is effected either prior to or subsequent to the addition of the mixed phosphorus component, and the resulting vanadium-phosphorus oxide catalyst precursor is recovered, dried and calcined.

Abstract: A process is provided for preparing fluid bed catalysts containing the mixed oxides of vanadium and phosphorus prepared from a mixed phosphoric acid source. A pentavalent vanadium compound is introduced into an organic liquid capable of reducing the vanadium, the vanadium is contacted with the mixed phosphoric acid source, the resulting catalyst precursor is comminuted, introduced into water to form an aqueous slurry and spray dried to form microspheroidal, fluidizable particles.