Process for preparing pyromellitic dianhydride

Details Process for preparing pyromellitic dianhydride Process for preparing pyromellitic dianhydride

1993-12-22

1995-02-07

Tsang, Cecilia

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

562410, 562412, 562415, C07D49300, C07C 5116

Patent

active

053876997

ABSTRACT:
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.

REFERENCES:
patent: 3576825 (1971-04-01), Bergman
patent: 4665200 (1987-05-01), Nakanishi et al.
patent: 4719311 (1988-01-01), Partonheimer
patent: 4824992 (1985-04-01), Tanaka
patent: 4867763 (1989-09-01), Scharf
Chem. Systems Reports: PERP 1987-T-4, 16-40.
SRI International, PEP Report 466, 1989, 2-4 to 2-6.
Patent Abstracts of Japan 55-122787 (Sep. 1980).

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