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Method and equipment for preparing terephthalic acid by air oxidation of p-xylene

A technology of terephthalic acid and p-xylene, which is applied in the field of preparing terephthalic acid by air oxidation of p-xylene, can solve the problems that it is not suitable for continuous industrial production, and the content of terephthalic acid cannot meet the requirements of industrial production.

Inactive Publication Date: 2009-02-11
HUNAN UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the reaction process disclosed in this patent is only suitable for the gap reaction process, not suitable for continuous industrial production, and the conversion rate of p-xylene and the content of terephthalic acid in the product cannot meet the requirements of industrial production
So far, there has been no report on the high yield of terephthalic acid directly from p-xylene through a continuous reaction process for metalloporphyrin or metalloporphyrin and metal salt catalyzed p-xylene system

Method used

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  • Method and equipment for preparing terephthalic acid by air oxidation of p-xylene
  • Method and equipment for preparing terephthalic acid by air oxidation of p-xylene

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Embodiment 1

[0016] The reaction equipment includes a reaction kettle with mechanical stirring and air distributor and a crystallization tank, and the oxidation reaction kettle and the crystallization separation tank are connected by pipelines and solid pumps at the same time. The production process is as follows: at 180°C, the metalloporphyrin dissolved in 2PPM structural formula (I) is introduced, R 1 = R 2 = R 3 =H, the p-xylene of M=Co, pass 18atm air through the gas distributor into the bottom of the stirred reactor, control the p-xylene flow rate so that the residence time is 100 minutes, control the air flow rate so that the tail oxygen content is no more than 6% . The reaction solution in the upper part of the stirring reactor overflows into the crystallization separation tank, and the solid suspension in the lower part of the stirring reaction tank enters the crystallization separation tank through a pump. The crystallization knockout tank was maintained at 155°C and 1 atm. Te...

Embodiment 2

[0018] The reaction equipment includes 2 reaction kettles with electric stirring and air distributor and 1 crystallization tank. The oxidation reaction kettle and the crystallization separation tank are connected by pipelines and solid pumps at the same time. The production process is as follows: at 185°C, the metalloporphyrin dissolved in 8PPM structural formula (II) is introduced, R 1 =CH 3 , R 2 = R 3 =H, M=Fe, p-xylene whose ligand X is Cl, pass 16atm oxygen-containing 18% oxygen-poor air through the gas distributor into the bottom of the stirred reactor 1, and stir the reaction liquid in the upper part of the reactor 1 Flow into the stirred reactor 2 through the overflow, the suspended reaction liquid in the lower part of the stirred reactor 1 is pumped into the stirred reactor 2 through a pump, and the oxygen-depleted air containing 18% oxygen is introduced into the stirred reactor 2. The p-xylene flow rate was controlled to give a residence time of 120 minutes. Cont...

Embodiment 3

[0020] The reaction equipment includes 3 reaction kettles with magnetic stirring and air distributor and 1 crystallization tank, and the oxidation reaction kettle and the crystallization separation tank are connected by pipelines and solid pumps at the same time. The production process is as follows: at 195 ° C, the metalloporphyrin dissolved in 50PPM structural formula (III) is introduced, R 1 =OCH 3 , R 2 = R 3 = H, M 1 = M 2=Mn p-xylene, 20atm oxygen-containing 23% oxygen-enriched air is passed through the gas distributor to the bottom of the stirred reactor 1, and the reaction liquid in the upper and lower parts of the reactor 2 enters the stirred reactor through the overflow and the pump respectively 2, feed oxygen-enriched air containing 23% oxygen into the stirred reactor 2, and the reaction solution in the upper and lower parts of the stirred reactor 2 enters the bottom of the stirred reactor 3 through overflow and pump respectively, and passes through the stirred ...

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Abstract

The invention discloses a method and equipment for preparing terephthalic acid by the air oxidation of p-xylene. The method is as follows: in the reaction system in which an oxidation reactor is connected with a crystallization separator in series, p-xylene containing metalloporphyrin catalyst or the mixing catalyst of metalloporphyrin and metal salt, and air, oxygen-diluted air, rich oxygen air or air with carbon dioxide are fed in the oxidation reactor and stay for 70 minutes to 180 minutes in the reactor at the temperature of 140 DEG C to 200 DEG C. The oxidation reaction mixture enters into a crystallizer for crystallization by overflow or pumping. The p-xylene, p-toluic acid and p-methyl benzyl alcohol obtained by separation is pumped into the oxidation reactor to be mixed with the p-xylene containing metalloporphyrin catalyst for secondary oxidation, and the fine terephthalic acid is obtained by purification after crystallization. The invention has the advantages that the p-xylene is directly oxidized into terephthalic acid by air, the energy consumption is low, the production efficiency is high, and the conversion rate of p-xylene and the yield of terephthalic acid can achieve more than 95 percent.

Description

technical field [0001] The present invention relates to a method and equipment for preparing terephthalic acid by air oxidation of p-xylene, in particular to a method for preparing terephthalic acid by air oxidation of p-xylene using metal porphyrin or metal porphyrin and metal salt as a catalyst and equipment. technical background [0002] Terephthalic acid is the main raw material for the polyester industry. At present, the industry mainly produces terephthalic acid by liquid-phase catalytic oxidation of p-xylene. The method uses acetic acid as a solvent, cobalt acetate and manganese acetate as a catalyst, and bromide as a promoter, and oxidizes p-xylene with air at 180-200° C. and 14-16 MPa. The conversion rate of p-xylene and the content of terephthalic acid in the product both reach more than 95%. But this method uses acetic acid as solvent, the content is 80%, and the content of p-xylene is less than 20%, and production efficiency is low, and energy consumption is b...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C63/26C07C51/265B01J31/22
CPCC07C51/265Y02P20/141Y02P20/52C07C63/26
Inventor 郭灿城罗伟平周然飞李国友龚天保刘强
Owner HUNAN UNIV
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