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Two stage oxidation process for production of aromatic dicarboxylic acids

A technology of benzenedicarboxylic acid and oxidation catalyst, which is applied in the field of oxidation and can solve the problems of high equipment cost and operating cost

Inactive Publication Date: 2004-07-14
GRUPO PETROTEMEX DE C V
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, acetic acid is over-oxidized (combusted) using excess oxygen, and because the process uses four-step oxidation to achieve the desired impurity levels, equipment and operating costs are high

Method used

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  • Two stage oxidation process for production of aromatic dicarboxylic acids

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Embodiment Construction

[0033] Our method is further illustrated by the following examples, where parts by weight are parts by weight. P-xylene and acetic acid in which the Co / Mn / Br catalyst system is dissolved are fed to the side of a first oxidation reactor 18 via conduit 10, air is fed to the bottom of this reactor via conduit 14, and the acetic acid containing dissolved catalyst is fed to the side of the first oxidation reactor 18. Speed ​​is 3.1 parts per minute, p-xylene is fed into reactor 12 through conduit 10 at a rate of 0.45 parts per minute, the latter is a cylindrical pressure vessel with a height: diameter ratio of 13.3, and air is fed at a rate of 2.0 parts per minute. Velocity is added through conduit 14 . The gas / liquid oxidation reaction mixture was filled to approximately 85% of the reactor volume, the temperature of the vigorously mixed reaction mixture was 160°C, the pressure was controlled at 6.2 bar absolute (90 psig), and the product in the oxidizer was 30% by weight in aqueou...

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Abstract

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 wherein the dialkyl benzene compound is oxidized with molecular oxygen to provide a first oxidation zone product comprising a benzenedicarboxylic acid containing minor amounts of mono-carboxylic acid by-products such as carboxybenzaldehyde and toluic acid. The first oxidation zone product comprising a slurry of a benzenedicarboxylic acid containing minor amounts of mono-carboxylic acid by-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 about 3% or less of the the rate of the feed of the molecular oxygen containing gas to the first oxidation zone. The benzenedicarboxylic acid product obtained contains a total concentration of carboxybenzaldehyde and toluic acid of about 150 ppmw or less.

Description

field of invention [0001] This invention relates to a novel process for the production of benzenedicarboxylic acids such as terephthalic acid by oxidation of dialkylbenzene compounds. More particularly, the present invention relates to an oxidation process wherein dialkylbenzene compounds are oxidized to benzenedicarboxylic acids in a two-step process using certain conditions to obtain benzenedicarboxylic acids of improved purity. background of the invention [0002] Aromatic dicarboxylic acids are produced by oxidation of dialkyl aromatic compounds, terephthalic acid (TPA) is produced commercially by liquid-phase oxidation of p-xylene in the presence of an oxidation catalyst such as Co-Mn-Br and a solvent such as acetic acid, isophthalic acid Produced by oxidation of m-xylene. The crude dicarboxylic acids produced by both methods contain colored impurities and monocarboxylic acids such as carboxybenzaldehyde, i.e. 4-carboxybenzaldehyde (4-CBA) for terephthalic acid and 3-c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07B61/00C07C51/265C07C63/26
CPCC07C51/265C07C63/26
Inventor R·B·舍帕德C·E·小苏姆纳B·A·滕南特
Owner GRUPO PETROTEMEX DE C V
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