Basf Aktiengesellschaft

Rolf Seubert

Johannes E Schmidt

Matthias Schwarzmann

Wilhelm Ruppel

Heinrich Aichinger

Peter Reuter

Friedrich Wirth

Friedrich Sauer

Karl Fischer

Gert Buerger

Karl-Heinz Boehning

Kurt Blechschmitt

Walter Scheidmeir

Dieter Zimmerling

Gerhard Michl

Phthalic anhydride is prepared in a multiple tube reactor provided with separate salt baths, the temperature of the salt bath used for cooling the first layer of catalyst, as regarded in the direction of flow of the reaction mixture, being from 2.degree. to 20.degree. C. higher than that of the salt bath(s) associated with the following layer(s).

Preparation of phthalic anhydride from o-xylene

Very pure maleic anhydride having a stable color is obtained by fractional distillation of crude maleic anhydride by a method in which the maleic anhydride vapor separated off from low boilers and high boilers is partially condensed so that from 0.5 to 15% by weight of the maleic anydride vapor is separated off from the vapor phase as a liquid precondensate, and the remaining very pure maleic anhydride vapor is then completely condensed.

Obtaining very pure maleic anhydride from crude maleic anhydride

Process for obtaining maleic anhydride that is not prone to discolor by treating crude maleic anhydride with oxygen, a gas mixture containing oxygen, or a substance that releases oxygen before or while it is distilled.

Obtaining maleic anhydride not prone to discolor

A supported catalyst containing vanadium and titanium, comprising a ring-shaped carrier having an external diameter of from 7.3 to 8.6 mm, a length of from 5.3 to 7 mm and a wall thickness of from 0.1 to 2 mm, and an active composition, applied thereto, of from 1 to 30 per cent by weight of vanadium pentoxide and from 70 to 99 per cent by weight of titanium dioxide and/or zirconium dioxide.

Supported catalyst containing vanadium and titanium

Growing community of inventors

Frankenthal, Germany

Rolf Seubert