Hoechst Aktiengesellschaft

Consortium Fur Elektrochemische Industrie Gmbh

Industrie Gmbh

Gelupas Gmbh

Werner Wagner

Wolfgang Anton Herrmann

Franz Grundei

Hans-Juergen Eberle

Richard Walter Fischer

Hans-Jurgen Eberle

Frank Muller

Georg Weichselbaumer

Ursula Volkhardt

Dieter M Fritz-Meyer-Weg

Erich Liebisch

Josef G Kuchler

The invention relates to a supported catalyst for gas-phase reactions having an inert support body and a surface coating comprising

Supported catalyst for gas-phase oxidation reactions

The invention relates to a process for preparing pyromellitic dianhydride (PMDA) by heterogeneously catalyzed oxidation in the gas phase by means of a gas containing molecular oxygen. The process involves oxidizing benzaldehydes which are 2,4,5-trialkylated by C.sub.1 - to C.sub.3 -alkyl groups or mixtures of benzaldehydes which are 2,4,5-trialkylated by C.sub.1 - to C.sub.3 -alkyl groups and benzenes which are 1,2,4,5-tetraalkylated by C.sub.1 - to C.sub.3 -alkyl groups in the presence of a catalyst. The catalyst contains as active components 5% to 95% by weight of one or more transition-metal oxides of sub-group IV of the Periodic Table of the Elements, from 1% to 50% by weight of one or more transition-metal oxides of sub-group V of the Periodic Table of the Elements. The catalyst also contains from 0% to 10% by weight of one or more oxides of elements of main group I of the Periodic Table of the Elements and/or from 0% to 50% by weight of one or more oxides of elements of main groups III, IV and V of the Periodic Table of the Elements and of elements of sub-groups VI and VII of the Periodic Table of the Elements. The indicated percentages by weight are based in each case on the total weight of the active components and add to 100% by weight.

Process for preparing pyromellitic dianhydride

The invention relates to a process for the metathesis of olefins which comprises reacting an olefin of the formula YCZ.dbd.CZ--(CX.sub.2).sub.n R.sup.2 (II) wherein

Organic derivatives of rhenium oxides and their preparation and use for

Use of organorhenium compounds for the oxidation of multiple C--C-bonds,

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Munich, Germany

Werner Wagner