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Method for refining pyromellitic anhydride by solvent

A technology for refining pyromellitic dianhydride and solvents, which is applied in organic chemistry and other fields, and can solve problems such as harsh environment, complicated operation, and difficulty in realizing industrialized production, and achieve the effects of less equipment, short process flow, and increased yield

Active Publication Date: 2008-08-27
常熟华虞环境科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] The aforementioned hot air flow carrying method is only a small-scale exploration, the process is immature and the yield is low, and it is difficult to realize industrial production
At present, all manufacturers in my country use the sublimation method to refine PMDA, but the method is complicated to operate, the labor intensity of workers is high, the environment is harsh, the pollution is serious, the yield is low (only 50-70%), and the energy consumption is high. improved, but still contains more organic impurities, only suitable for the production of low-grade powder coatings, and cannot meet the needs of foreign manufacturers for high-quality PMDA products

Method used

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  • Method for refining pyromellitic anhydride by solvent

Examples

Experimental program
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Effect test

Embodiment 1

[0025] Add 97.2% crude pyromene directly obtained and sold from durene raw material through air catalytic oxidation by Wuhan Hannan Tongxin Chemical Co., Ltd. 108kg of formic anhydride, 600kg of acetic anhydride with a content of 98.9%, and 12kg of activated carbon, that is, the feeding ratio is 9:50:1. After the feeding is completed, the upper cover of the feeding manhole is closed, and the stirring is started. At the same time, the steam valve is opened to allow steam to enter the enamel kettle clamp. Start heating the cover, keep the temperature of the material in the enamel kettle at 125°C and react for 110 minutes under constant stirring. After the reaction is over, start to vacuumize the enamel crystallization kettle. The material is introduced into the pipeline by the preferred but not limited to the JLBF type composite bag fine filter produced and sold by Qidong Julong Petrochemical Equipment Co., Ltd. In the jacketed enamel crystallization kettle, while stirring, pass...

Embodiment 2

[0027] Add 97.7% crude pyromellitidine directly obtained and sold by air catalytic oxidation of durene raw material by Wuhan Hannan Tongxin Chemical Co., Ltd. Acid anhydride 72kg, after carrying out a PMDA refining reaction, content is 95.6% acetic anhydride 540kg, active carbon 9kg, promptly charging ratio is 8: 60: 1, after feeding completes, close the feeding manhole loam cake, open and stir, open steam valve simultaneously Steam enters the jacket of the enamel kettle to start heating. Keep the temperature of the material in the enamel kettle at 118°C and react for 90 minutes under constant stirring. After the reaction, start to vacuum the enamel crystallization kettle. When the vacuum reaches 0.08MPa, open the bottom of the enamel reaction kettle Valve, the material in the kettle is introduced from the pipeline to the preferred but not limited to JLBF type composite bag fine filter produced and sold by Qidong Julong Petrochemical Equipment Co., Ltd., Jiangsu Province, China...

Embodiment 3

[0029] Add 97.2% crude pyromellitidine directly obtained and sold by air catalytic oxidation of durene raw material by Wuhan Hannan Tongxin Chemical Co., Ltd. 56 kg of acid anhydride, 440 kg of 93.2% acetic anhydride and 12 kg of active carbon after the secondary PMDA refining reaction, that is, the feeding ratio is 7: 55: 1.5. After the feeding is completed, the upper cover of the feeding manhole is closed, the stirring is started, and the steam valve is opened simultaneously. Let the steam enter the jacket of the enamel kettle to start heating, keep the temperature of the material in the enamel kettle at 112°C and react for 120 minutes under constant stirring. After the reaction is completed, start the enamel / vacuum. When the vacuum reaches 0.08MPa, open the bottom valve of the enamel reaction kettle , the material in the kettle is introduced into the preferred but not limited to JLBF composite bag-type fine filter produced and sold by Qidong Julong Petrochemical Equipment Co...

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Abstract

A method for refining pyromellitic dianhydride via solvent belongs to the preparation technical field of pyromellitic dianhydride, which comprises adding crude pyromellitic dianhydride, dehydrating agent and decolorant into a reaction vessel, heating, mixing and reacting, after the reaction, filtering immediately, cooling and crystallizing the filtered liquor in a crystallization vessel, filtering the crystallized materials to separate and remove crystallization mother liquor to obtain pyromellitic dianhydride crystal containing mother liquor, drying and cooling to obtain refined final product of pyromellitic dianhydride, wherein the crystallization mother liquor removed by filtering is circulated. The invention has the advantages that the invention can improve yield of PMDA, save dehydrating agent and decolorant, save energy and reduce energy consumption, the product PMDA has high purity, the organic impurties in product as trimellitic anhydride, pyromellitic acid dianhydride, pyromellitic acid dianhydride monoanhydride and pentamethyl anhydride are reduced, thereby reaching the purity demand for polymerizing electronic grade polyimide film.

Description

technical field [0001] The invention belongs to the technical field of preparation of pyromellitic dianhydride, and in particular relates to a method for refining pyromellitic dianhydride with a solvent. Background technique [0002] The English name of pyromellitic dianhydride is Pyromellitic Dianhydride (abbreviated as PMDA, the same below), which is mainly used for the synthesis of polyimide, because polyimide has excellent ultra-high heat resistance, acid and alkali resistance, excellent Due to its excellent mechanical properties, electrical properties and dimensional stability, it is widely used in high-tech fields such as aviation, aerospace, microelectronics and atomic energy, which have strict requirements on material properties. [0003] Since the early 1960s, DuPont of the United States first developed the benzoic polyimide and commercialized it into the market, because of its high heat resistance level and the excellent comprehensive performance mentioned above. ...

Claims

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Application Information

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IPC IPC(8): C07D493/04
Inventor 苏仁球刘忠云赵海峰王玉山陈丽萍顾雪良
Owner 常熟华虞环境科技有限公司
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