TWO STAGE OXIDATION PROCESS FOR THE PRODUCTION OF AROMATIC DICARBOXYLIC ACIDS

摘要

Disclosed is a process for producing a benzenedicarrboxylic acid such as terephthalic acid wherein a dialkyl benzene compound and acetic acid having catalyst components dissolved therein are fed to a first reaction zone where in the dialkyl benzene compound is oxidized with molecular oxygen to provide a first oxidation zone product comprising a benzenedicarboxylic acid containin g minor amounts of mono-carboxylic acid by-products such as carboxybenzaldehyd e and toluic acid. The first oxidation zone product comprising a slurry of a benzene-dicarboxylic acid containing minor amounts of mono-carboxylic acid b y- products is fed to a second oxidation reaction zone that is operated under more severe conditions of temperature and pressure. The rate of the feed of a molecular oxygen containing gas to the second oxidation zone is 3 % or less of the rate of the feed of the molecular oxygen containing gas to the first oxidation zone. The benzenedicarboxylic acid product obtained contains a tot al concentration of carboxybenzaldehyde and toluic acid of 150 ppmw or less.