Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
1999-04-16
2000-07-04
Owens, Amelia
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C07D49300
Patent
active
060841095
ABSTRACT:
The present invention relates to a process for preparing pyromellitic dianhydride via an oxidation in gas phase under normal pressure. The process is characterized in that a catalyst system is used, which catalyst system comprises a catalyst which is a mixture of vanadium and tungsten oxides; a catalyst support comprising rutile and at least one material selected from the group consisting of tungsten carbide, silicon carbide and a mixture thereof; and a cocatalyst comprising oxides of manganese, antimony, bismuth, phosphorus, copper, aluminum, titanium or a mixture thereof, an oxide of an element of the VIIIB group of the periodic table, and an oxide of an alkali metal and/or alkaline earth metal. In this process, pyromellitic dianhydride is produced from a feedstream containing 1,2,4,5-tetraalkylbenzene in a gas flow rate of 4,000.about.12,000 hr.sup.-1 via a selective oxidation at 300.about.450.degree. C. in the presence of air which acts as an oxidant.
REFERENCES:
patent: 4665200 (1987-05-01), Nakanishi et al.
patent: 4694089 (1987-09-01), Kosaka et al.
patent: 5387699 (1995-02-01), Wagner
Chu Shiao-Jung
Hwang Chian-Liang
Chinese Petroleum Corp.
Owens Amelia
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