Basf Aktiengesellschaft

Paul Hornberger

Friedrich Wirth

Peter Reuter

Kurt Blechschmitt

Gert Buerger

Joachim Wagner

Wolfgang Kube

Otto Leman

Dieter Karau

A process for the manufacture of phthalic anhydride by oxidizing o-xylene and/or naphthalene over a supported catalyst containing vanadium pentoxide and titanium dioxide, at from 350.degree. to 500.degree. C, in which the o-xylene or naphthalene is passed, with an oxygen-containing carrier gas, over the catalyst, and in which the catalyst in the first 25-50 per cent by volume of the total catalyst volume, in the direction of flow of the mixture of o-xylene or naphthalene and carrier gas, contains from 0.01 to 0.3 per cent by weight, based on titanium dioxide, of rubidium, but no phosphorus, in the active composition, while the remainder of the catalyst contains from 0.02 to 0.8 per cent by weight, based on titanium dioxide, of phosphorus, but no rubidium, in the active composition.

Manufacture of phthalic anhydride from o-xylene or naphthalene

Process for the recovery of phthalic anhydride in which gases as obtained in the catalytic atmospheric oxidation of o-xylene or naphthalene are treated with a hydrocarbon containing C.sub.26.sub.- paraffins, cooling, if necessary, the hydrocarbon laden with phthalic anhydride, separating the solid phthalic anhydride followed by melting and distillation thereof.

Recovery of phthalic anhydride

Supported catalyst for the oxidation of o-xylene or naphthalene to phthalic anhydride, comprising an inert carrier and the active material applied thereto, which contains from 1 to 40 per cent by weight of vanadium pentoxide, from 60 to 98.84 per cent by weight of titanium dioxide and from 0.16 to 0.6 per cent by weight, based on titanium dioxide, of rubidium in the form of rubidium oxide, the vanadium pentoxide content being from 0.05 to 4 per cent by weight, based on the (complete) catalyst.

Supported catalyst for the oxidation of o-xylene and/or naphthalene to

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Ludwigshafen, Germany

Paul Hornberger