PRODUCTION OF PHTHALIC ANHYDRIDE BY GAS PHASE OXIDATION OF O-XYLOL

WIPO Patent Application WO2007135104

A8

The invention relates to a method for producing phthalic anhydride by catalytic gas phase oxidation of o-xylol. According to said method, a gaseous mixture of o-xylol and an oxygen-containing gas is guided through at least two reaction zones in a main reactor, the temperature of said reaction zones being adjustable independently of each other, and is reacted to give a gaseous intermediate reaction product which contains unreacted o-xylol, phthalic anhydride reaction products with a lower oxidation state and phthalic anhydride, and the intermediate reaction product is introduced into a secondary reactor. The temperature in the reaction zones in the primary reactor is controlled in such a manner that the concentration of the unreacted o-xylol in the intermediate reaction product is at least 0.5% by weight. The method according to the invention allows an increase in total yield of phthalic anhydride without any or without substantial decrease in product quality.

WO/2007/116018	CATALYST SYSTEM FOR PREPARING CARBOXYLIC ACIDS AND/OR CARBOXYLIC ANHYDRIDES
JPH03101673	SYNTHESIS OF 3,3',5,5',6,6'-HEXAFLUORO-4,4'-BIPHTHALIC ANHYDRIDE, AND 3,3',5,5',6,6'-HEXAFLUORO-4,4'-BIPHTHALIC ANHYDRIDE AND ITS INTERMEDIATE

MACKEWITZ THOMAS (DE)
ROSOWSKI FRANK (DE)
TENTEN ANDREAS (DE)

PCT/EP2007/054841

June 12, 2008

May 18, 2007

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BASF SE (DE)
MACKEWITZ THOMAS (DE)
ROSOWSKI FRANK (DE)
TENTEN ANDREAS (DE)

C07D307/89

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