Vanadium/phosphorus mixed oxide catalyst, process for its preparaton and its use
AssigneeBayer Aktiengesellschaft
InventorsHeinz-Jurgen Alpers, Karl-Heinz Heller, Gunther Lenz
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Abstract
The invention relates to a vanadium/phosphorus mixed oxide catalyst, a process for its preparation and its use for the preparation of maleic anhydride. The catalyst according to the invention is prepared by reacting a vanadium(V) compound with phosphoric acid and/or a compound forming phosphoric acid with heating, optionally in the presence of water, and subsequently treating the product obtained after the reaction with organic solvents and/or diluents having reducing activity, optionally in the presence of a promoter, at an elevated temperature.
Claims30
A process for the preparation of vanadium phosphorus mixed oxide-containing catalysts comprising
- (a) introducing a pentavalent vanadium compound and a pentavalent phosphorus compound into an aqueous medium wherein the aqueous medium is free from agents which would substantially reduce the pentavalent vanadium compound;
- (b) forming a substantially pentavalent catalyst precursor in the aqueous medium;
- (c) recovering the pentavalent catalyst percursor from the aqueous medium;
- (d) introducing the pentavalent catalyst precursor into a substantially organic liquid medium capable of reducing at least a portion of the vanadium to a valence state of about +4;
- (e) effecting reduction of the vanadium;
- (f) recovering the resulting partially reduced catalyst precursor from the organic liquid medium;
- (g) calcining the partially reduced catalyst precursor, which further comprises introducing a promoter element-containing compound into the aqueous medium, or into the organic liquid medium prior or subsequent to the reduction of the vanadium.
An oxidation catalyst comprising mixed oxides of vanadium and phosphorus prepared by
- (a) introducing a pentavalent vanadium compound and a pentavalent phosphorus compound into an aqueous medium wherein the aqueous medium is free from agents which would substantially reduce the pentavalent vanadium compound;
- (b) forming a substantially pentavalent catalyst precursor in the aqueous medium;
- (c) recovering the pentavalent catalyst precursor from the aqueous medium;
- (d) introducing the pentavalent catalyst precursor into a substantially organic liquid medium capable of reducing at least a portion of the vanadium to a valence state of about +4, the catalyst additionally containing a promoter element selected from the group consisting of Mn, Co, Fe, Zn, Ni, Cu, Cd or mixtures thereof.
Dependencies are inferred from the claim text.