US 4,361,501 A · Preparation of vanadium phosphorus catalysts using a mixed phosphorus source

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.

Claims15

Dependent claims

A process for the preparation of oxidation catalysts containing the mixed oxides of vanadium and phosphorus which comprises

(a) introducing a pentavalent vanadium-containing compound into a liquid medium, capable of reducing the valence state of said vanadium;
(b) effecting reduction of at least a portion of said vanadium to a valence state of about +4;
(c) adding a mixed phosphorus component comprising 45-90% by weight orthophosphoric acid and 10-50% by weight pyrophosphoric acid to said medium prior to or subsequent to effecting said reduction to form a catalyst precursor;
(d) recovering the catalyst precursor;
(e) drying the catalyst precursor;
(f) calcining the catalyst precursor.

3 more elements

Dependencies are inferred from the claim text.

Preparation of vanadium phosphorus catalysts using a mixed phosphorus source

Life of this patent

Preparation of vanadium phosphorus catalysts using a mixed phosphorus source

Life of this patent

Abstract

Claims15