Bayer Aktiengesellschaft

Karl-Heinz Heller

Gunther Lenz

Heinz-Jurgen Alpers

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.

Vanadium/phosphorus mixed oxide catalyst, process for its preparaton and

A process for the recovery of maleic anhydride from distillation residues containing the same is described whereby a residue containing phthalic anhydride is added to the residue of maleic anhydride prior to or after distillation of the maleic anhydride residue. By such a process maleic anhydride recovery is improved and the distillation residue remaining from distillation of the maleic anhydride out of the maleic anhydride residue remains removable by simple mechanical means from the distillation vessel.

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Krefeld, Germany

Karl-Heinz Heller