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Method for synthesizing pyromellitic dianhydride through durene liquid-phase continuous oxygen-enriched precise oxidation

A technology of pyromellitic dianhydride and pyromellitic acid is applied in the field of synthesizing pyromellitic dianhydride by liquid-phase oxidation of pyromellitic tetratoluene, and can solve the problems of difficulty in product separation and purification, low reaction conversion rate and high reaction temperature problems, to achieve the effect of eliminating the need for recrystallization or sublimation purification process, high purity and efficient heat transfer

Pending Publication Date: 2021-11-02
JIANGSU ZHENGDAN CHEM IND CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] 1) The reaction temperature is high, and the reaction energy consumption is large;
[0009] 2) The reaction conversion rate is not high, and there are many by-products;
[0010] 3) The process route is long and the product separation and purification are difficult

Method used

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  • Method for synthesizing pyromellitic dianhydride through durene liquid-phase continuous oxygen-enriched precise oxidation

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] The mixture of durene, acetic acid and cobalt-manganese-zinc-bromine catalyst (mass ratio 5:94.99:0.01) is continuously poured into the microchannel reactor, and the air is continuously introduced into the microchannel device at the same time as the liquid is injected, and the microchannel reaction The inner diameter of the microchannel is 10 µm.

[0023] The cobalt manganese zinc bromine catalyst is a mixture of cobalt acetate, manganese acetate, zinc acetate and tetrabromoethane, wherein the molar ratio of cobalt, manganese, zinc and bromine is 1:1:0.5:0.5.

[0024] Keep the temperature in the microchannel reactor at 180°C and the pressure in the reactor at 1.2 MPa. The pyromellitic acid is generated by the catalytic reaction between durene and oxygen, and the generated reaction solution rich in pyromellitic acid is discharged continuously. The content of tetracarboxylic acid is 98.5%.

[0025] Cool the pyromellitic acid reaction solution to 25°C to crystallize, ente...

Embodiment 2

[0027] The mixed solution of durene, acetic acid and cobalt-manganese-zinc-bromine catalyst (mass ratio 17:82.98:0.02) is continuously poured into the microchannel reactor, and oxygen-enriched gas, oxygen content of 30%, and the inner diameter of the microchannel of the microchannel reactor is 10µm.

[0028] The cobalt manganese zinc bromine catalyst is a mixture of cobalt acetate, manganese acetate, zinc acetate and tetrabromoethane, wherein the molar ratio of cobalt, manganese, zinc and bromine is 1:1:0.5:0.5.

[0029] Keep the temperature in the microchannel reactor at 260°C and the pressure in the reactor at 1.8 MPa. The pyromellitic acid is generated by the catalytic reaction between durene and oxygen, and the generated reaction solution rich in pyromellitic acid is discharged continuously. The content of tetracarboxylic acid is 98.6%.

[0030] Cool the pyromellitic acid reaction solution to 25°C to crystallize, enter the centrifuge for separation, remove acetic acid, wa...

Embodiment 3

[0032] The mixed solution of durene, acetic acid and cobalt-manganese-zinc-bromine catalyst (mass ratio 10:89.95:0.05) is continuously poured into the microchannel reactor, and oxygen-enriched gas, oxygen content of 50%, and the inner diameter of the microchannel of the microchannel reactor is 20µm.

[0033] The cobalt manganese zinc bromine catalyst is a mixture of cobalt acetate, manganese acetate, zinc acetate and tetrabromoethane, wherein the molar ratio of cobalt, manganese, zinc and bromine is 1:1:0.5:0.5.

[0034] Keep the temperature in the microchannel reactor at 220°C and the pressure in the reactor at 1.4 MPa. The pyromellitic acid is generated by the catalytic reaction between durene and oxygen, and the generated reaction liquid rich in pyromellitic acid is discharged continuously. The pyromellitic acid in the reaction liquid is The content of tetracarboxylic acid is 98.8%.

[0035] Cool the pyromellitic acid reaction solution to 25°C to crystallize, enter the cen...

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Abstract

The invention discloses a method for synthesizing pyromellitic dianhydride through durene liquid-phase continuous oxygen-enriched precise oxidation in the technical field of organic chemical synthesis. The method comprises the following steps: firstly, proportioning and feeding: completely mixing durene, acetic acid and a cobalt-manganese-zinc-bromine catalyst according to the mass percent of (5-20%): (79.97-94.99%): (0.01-0.05%), and continuously pumping the mixed solution and oxygen-enriched gas into a micro-channel reactor for oxidation reaction; carrying out catalytic reaction to generate pyromellitic acid, and continuously discharging the generated reaction liquid rich in pyromellitic acid; then crystallizing and centrifuging, and removing acetic acid, water and the catalyst to obtain a filter cake, namely refined pyromellitic acid; and finally, dehydrating into anhydride to obtain the pyromellitic dianhydride. The method has the characteristics of high-speed mixing, efficient heat transfer, short reactant retention time, high conversion rate, no recrystallization or sublimation purification process, convenience in control, low oxidation reaction energy consumption, high safety coefficient, high reaction product purity and no amplification effect.

Description

technical field [0001] The invention relates to the technical field of organic chemical synthesis, in particular to a method for synthesizing pyromellitic dianhydride by liquid-phase oxidation of durene. Background technique [0002] Durene, also known as durene, is an important organic chemical raw material. Durene is mainly used to produce pyromellitic acid, and then dehydrated to obtain pyromellitic dianhydride. Pyromellitic dianhydride is an important raw material for the production of polyimide polymers. Polyimide is a new type of synthetic material with high temperature resistance, low temperature resistance, radiation resistance, impact pressure and excellent electrical and mechanical properties. It has an irreplaceable important use of engineering plastics in the mechanical and electrical industries. With the continuous expansion of the polyimide market, the demand for durene as the main raw material for its synthesis is also increasing day by day. [0003] The pr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D493/04
CPCC07D493/04
Inventor 曹正国李江华王福任伟荆晓平
Owner JIANGSU ZHENGDAN CHEM IND CO LTD
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