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Crystal pelleting and purifying method of aromatic carboxylic acid products

A technology of aromatic carboxylic acid anhydrides and aromatic carboxylic anhydrides, which is applied in the field of crystallization, granulation and purification of aromatic carboxylic anhydride products, and can solve problems such as inconvenient use, production of process wastewater, and dust pollution

Inactive Publication Date: 2009-07-01
TIANJIN UNIVERSITY OF TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The process route is long, there is process waste water, the material loss and pollution are serious in the sublimation process, the product yield is low, and the obtained product is powdery, there is serious dust pollution in the process of processing and use, the use performance is not good, and it is inconvenient to use
[0004] In order to solve the refining problem of pyromellitic dianhydride, Japanese published patent No. 454050 proposes the recrystallization refining method using dioxane-acetic anhydride mixture as solvent, Japanese published patent No. 5058024 proposes the method of washing with mixed solvents, U.S. patent USP4370487 proposed a complex separation method, so far, there is no report about product crystallization and granulation

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] In a 500mL four-necked bottle, add 100 parts of acetic acid and 100 parts of acetic anhydride to prepare a mixed solvent of acetic acid / acetic anhydride, heat up to 60°C in 10-30 minutes while stirring, and add 50 parts of crude pyromellitic acid with a purity of 98.35% Dianhydride, heated up to reflux temperature of 122-124°C in 20-30 minutes with stirring, acted at this temperature for 1 hour, cooled with water bath for about 1 hour to below 20°C with stirring, filtered to obtain granular crystalline solid, vacuum After drying, 45 parts of white or light yellow pyromellitic dianhydride crystalline products were obtained, with a product yield of 90% and a purity of 99.24%.

Embodiment 2

[0023] In a 500mL four-necked bottle, add 90 parts of acetic acid and 210 parts of acetic anhydride to prepare a mixed solvent of acetic acid / acetic anhydride, heat up to 80°C in 20-30 minutes while stirring, and add 50 parts of crude pyromellitic acid with a purity of 98.26% Dianhydride and 3g of activated carbon, heated up with stirring to dissolve completely, and acted at reflux temperature for 0.5 hours, filtered while hot, collected mother liquor, cooled to below 20°C with a water bath for about 30 minutes under stirring, filtered, and obtained granular crystalline solid , vacuum-dried to obtain 41 parts of white or light yellow pyromellitic dianhydride crystalline products, the product yield was 82%, and the purity was 99.34%.

Embodiment 3

[0025] In a 500mL four-necked bottle, add 125 parts of acetone and 125 parts of acetic anhydride to prepare a mixed solvent of acetone / acetic anhydride, heat up to the reflux temperature in 20-30 minutes while stirring, and add 50 parts of crude pyromellitic acid with a purity of 98.26% Dianhydride and 5 parts of activated carbon, heated up to dissolve completely under stirring, and acted at reflux temperature for 0.5 hours, filtered while hot, collected mother liquor, cooled to below 15°C with water bath and then ice-water bath under stirring, filtered, and obtained granular The crystalline solid was vacuum-dried to obtain 39 parts of white pyromellitic dianhydride crystalline product, the product yield was 78%, and the purity was 99.53%.

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Abstract

The method for crystallization, granulation and purification of aromatic carboxylic anhydride products relates to a technology for crystallization, granulation and purification of aromatic carboxylic anhydride products. The described invention method is: add lower aliphatic carboxylic acid anhydride in reaction kettle such as: one in acetic anhydride, propionic anhydride, succinic anhydride or a kind of in the mixture thereof, or contain the mixing of above-mentioned lower aliphatic carboxylic anhydride Solvent, heat, add crude aromatic carboxylic anhydride and adsorption decolorizer equivalent to 0-50% of aromatic carboxylic anhydride under stirring for 0.1-10 hours, or boil the crude aromatic carboxylic anhydride at reflux temperature 0.1-10 hours, then carry out hot filtration, concentrate the filtrate or not, cool, filter, and dry to obtain fine aromatic carboxylic acid anhydride granular or aromatic carboxylic acid polyanhydride crystals. Using the method of the invention to crystallize, granulate and purify aromatic carboxylic acid anhydride products solves the problems of product crystallization, granulation and dust pollution, and improves product purity and performance.

Description

technical field [0001] The invention relates to the manufacture of aromatic carboxylic anhydride products, in particular to the crystallization, granulation and purification method and technology of aromatic carboxylic anhydride products. Background technique [0002] At present, active aromatic carboxylic acid anhydrides directly produced by various reactions in industry, such as pyromellitic dianhydride, phthalic anhydride, substituted phthalic anhydride, naphthalene anhydride, substituted naphthalene anhydride, etc., are usually powdery products and contain various impurities , needs to be purified and crystallized to meet higher application requirements. Due to the active chemical properties of aromatic carboxylic acid anhydride compounds, they are easy to react with various substances. During the refining and crystallization granulation process, various side reactions are often accompanied, which reduces the quality of the product. Therefore, crystallization, granulati...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C51/54C07C51/573C07C51/42C07C51/43
Inventor 卢俊瑞鲍秀荣佐毅
Owner TIANJIN UNIVERSITY OF TECHNOLOGY
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