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Method for separating and purifying 2, 6-naphthalene dicarboxylic acid

A technology of naphthalene dicarboxylic acid and naphthalene dicarboxylate, which is applied in the separation/purification of carboxylic acid compounds, preparation of carboxylate, preparation of carboxylate, etc. It can solve problems such as poor color, low product purity, and high impurity content , to achieve the effect of reducing impurity content, improving product purity and chroma, and good technical effect

Pending Publication Date: 2021-04-20
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a method for separating and purifying 2,6-naphthalene dicarboxylic acid in order to overcome the problems of low product purity, poor color and high impurity content in the existing 2,6-NDA separation and purification method

Method used

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  • Method for separating and purifying 2, 6-naphthalene dicarboxylic acid
  • Method for separating and purifying 2, 6-naphthalene dicarboxylic acid
  • Method for separating and purifying 2, 6-naphthalene dicarboxylic acid

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Embodiment approach

[0074] According to a preferred embodiment of the present invention, the method also includes the salt solution obtained by mixing the material to be salted and purified containing 2,6-naphthalene dicarboxylic acid with solvent I, the solution, and the 2,6-naphthalene dicarboxylic acid containing At least one of the first crystallization solution obtained by dissolving the raw material of formic acid in solvent V-1 and the second crystallization solution obtained by dissolving the 2,6-naphthalene dicarboxylic acid crystal I in solvent V-2 is used for impurity removal.

[0075]The impurity removal can be carried out according to conventional technical means in the art. Preferably, the impurity removal agent used in the impurity removal is selected from ion exchange resins, macroporous adsorption resins, saturated aqueous solutions of sodium bisulfite and saturated aqueous solutions of potassium bisulfite. At least one of the aqueous solutions.

[0076] According to a preferred ...

Embodiment 1

[0091] According to the separation and purification method of 2,6-NDA described in the present invention, such as figure 1 shown;

[0092] Salt purification:

[0093] A) The purity of 2,6-naphthalene dicarboxylic acid in the raw material containing 2,6-naphthalene dicarboxylic acid is 99%, wherein the concentrations of impurity ions cobalt, manganese, and bromine are respectively 1000 μg / g, 1500 μg / g, and 500 μg / g, The content of 2-formyl-6-naphthoic acid is 4000 μg / g, and the content of 2-acetyl-6-naphthoic acid is 2000 μg / g. The raw material containing 2,6-naphthalene dicarboxylic acid and triethylamine aqueous solution (solvent I , the concentration is 90% by weight) and acetone (solvent II) are mixed to obtain crystals containing 2,6-naphthalene dicarboxylate;

[0094] B) using water (solvent III) to dissolve crystals of 2,6-naphthalene dicarboxylate to obtain a solution, and adding powdered activated carbon to decolorize the solution;

[0095] C) Acetic acid (solvent I...

Embodiment 2

[0102] According to the separation and purification method of 2,6-NDA described in the present invention, such as figure 1 shown;

[0103] Salt purification:

[0104] A) The purity of 2,6-naphthalene dicarboxylic acid in the raw material containing 2,6-naphthalene dicarboxylic acid is 99%, wherein the concentrations of impurity ions cobalt, manganese, and bromine are respectively 1000 μg / g, 1500 μg / g, and 500 μg / g, The content of 2-formyl-6-naphthoic acid is 4000 μg / g, the content of 2-acetyl-6-naphthoic acid is 2000 μg / g, the raw material containing 2,6-naphthalene dicarboxylic acid and triethylamine aqueous solution (concentration is 80% by weight) and acetone are mixed to obtain crystals containing 2,6-naphthalene dicarboxylate;

[0105] B) using water to dissolve the crystals of 2,6-naphthalene dicarboxylate to obtain a solution, adding powdered activated carbon to decolorize the solution;

[0106] C) adding acetic acid to the decolorized solution to precipitate 2,6-nap...

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Abstract

The invention relates to the field of production of 2, 6-naphthalene dicarboxylic acid, and discloses a method for separating and purifying 2, 6-naphthalene dicarboxylic acid, which comprises the steps of salifying and purifying and crystallizing and purifying before and / or after salifying and purifying, the salifying purification comprises the following steps: mixing a to-be-salified and purified material containing 2, 6-naphthalene dicarboxylic acid with a solvent I, and then separating out crystals of 2, 6-naphthalene dicarboxylic acid; dissolving the crystal of 2, 6-naphthalene dicarboxylic acid by using a solvent III to obtain a dissolved solution; adding a solvent IV into the dissolved solution to separate out 2, 6-naphthalene dicarboxylic acid, and carrying out solid-liquid separation to obtain a 2, 6-naphthalene dicarboxylic acid crystal I; the crystallization purification step performed before salifying purification comprises the following steps: dissolving a raw material containing 2, 6-naphthalene dicarboxylic acid in a solvent, and carrying out first recrystallization to obtain a to-be-salified purification material containing 2, 6-naphthalene dicarboxylic acid; and the crystallization purification step after salifying purification comprises the following sub-steps: dissolving the 2, 6-naphthalene dicarboxylic acid crystal I in a solvent, and carrying out second recrystallization to obtain the 2, 6-naphthalene dicarboxylic acid crystal. The method provided by the invention can improve the purity and chromaticity of the product and reduce the impurity content.

Description

technical field [0001] The invention relates to the field of 2,6-naphthalene dicarboxylic acid production, in particular to a method for separating and purifying 2,6-naphthalene dicarboxylic acid. Background technique [0002] 2,6-naphthalene dicarboxylic acid (2,6-NDA) is an important raw material for the preparation of new polyester PEN and liquid crystal polymer LCP, and its preparation methods mainly include 2,6-dimethylnaphthalene oxidation, 2,6 -Diisopropylnaphthalene oxidation method, 2-methylnaphthalene acylation oxidation method, Henkel method, carboxyl transfer method, etc. The 2,6-NDA obtained by the above preparation method is a homogeneous crude product, in which there are inevitably many impurities, and further separation and purification are required to meet the requirements of the subsequent polymerization reaction to prepare PEN and LCP. [0003] The separation and purification methods of 2,6-NDA mainly include esterification hydrolysis method, catalytic hy...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/41C07C51/47C07C51/02C07C51/43C07C63/38C07C209/68C07C211/05
Inventor 陈亮曹禄吴成跃秦春曦
Owner CHINA PETROLEUM & CHEM CORP