Bayer Aktiengesellschaft

Gunther Lenz

Karl-Heinz Heller

Hugo Vernaleken

Uwe Hucks

Josef Merten

Heinrich Krimm

Kurt Weirauch

Heinz-Jurgen Alpers

Hermann Schnell

Horst-Gunter Kassahn

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.

Process for the recovery of maleic anhydride from distillation residues

1. High molecular weight, high-impact, readily processible moulding compositions of mixtures of: (a) aromatic N-alkyl polyurethanes corresponding to the following general formula: ##STR1## WHEREIN R.sup.1 represents methyl or ethyl;

N-Alkyl polyurethane/vinyl polymer mixtures

A continuous process for the production of a bisphenol bischlorocarbonic acid ester wherein an aqueous solution of a dialkali metal salt of a hydroquinone or a bisphenol is reacted in a pump circulating system with 2.5 to 5.0 mol, per mol of dihydroxy compound of phosgene dissolved in a suitable solvent for the bischlorocarbonic acid ester formed in the reaction under the addition of an alkali metal hydroxide solution to keep the pH-value between 9.0 and 12.0, the organic phase obtained is separated wherefrom the bisphenol bischlorocarbonic acid ester is isolated by distillation and/or crystallisation.

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Krefeld, Germany

Gunther Lenz