The production method of high-purity 2,6-naphthalene dicarboxylic acid

A technology of naphthalene dicarboxylic acid and production method, which is applied in the separation/purification of carboxylic acid compounds, organic chemistry and other directions, can solve the problems of a large number of solid absorbents and solvents, insufficient optimization of operating conditions, deterioration of color quality, etc., and achieves reduction of solvent circulation. The effect of reducing the energy consumption of the system and increasing the average particle size

Active Publication Date: 2021-08-03
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method requires a large amount of solid absorbent and solvent, and, along with the crystallization of all monoalkali metal salts, salts generated from impurities such as NA or FNA also crystallize out, thus causing separation difficulties
In addition, alkali metals remain in the crystals of 2,6-NDCA, thereby deteriorating the chromaticity at the time of polymerization, and causing disadvantages in terms of crystal size and yield
[0012] The above refining methods all use relatively complicated processes and expensive solvents, or use water as the solvent but the solubility of 2,6-NDCA is low due to insufficient operating conditions, and the solvent circulation is large and energy consumption is high

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] The purity of the crude 2,6-NDCA is 90%, the concentration of the slurry produced by the crude 2,6-NDCA in the mixing step is 8%, the temperature in the dissolution tank A is maintained at 330°C and 13MPa, and the dissolved slurry is sequentially Through the crystallization unit, each crystallization process lasts 60 minutes, using 4 crystallization units in series to carry out the process, in the case of four crystallization units in series, their temperature and pressure are respectively set as follows: set their temperature and the pressure were set as: 285°C and 9MPa in the first crystallization unit B, 265°C and 6.5MPa in the second crystallization unit C, 245°C and 5MPa in the third crystallization unit D, 200°C and 200°C in the fourth crystallization unit E 3.5MPa. After crystallization, the product 3 and mother liquor 4 are obtained through the solid-liquid separation unit. The ratio of the mother liquor 6 discharged from the system to the mother liquor 5 returne...

Embodiment 2

[0034] The purity of the crude 2,6-NDCA is 90%, the concentration of the slurry produced by the crude 2,6-NDCA in the mixing step is 10%, the temperature in the dissolution tank A is maintained at 340°C and 15MPa, and the dissolved slurry is sequentially Through the crystallization unit, each crystallization process lasts 60 minutes, using 3 crystallization units in series to carry out the process, and in the case of 3 crystallization units in series, their temperature and pressure are respectively set as follows: set their temperature The pressure and temperature are respectively set as: 300°C and 10MPa in the first crystallization unit B, 270°C and 7MPa in the second crystallization unit C, 230°C and 3MPa in the third crystallization unit D, and the product is obtained through the solid-liquid separation unit G after crystallization And the mother liquor, the mother liquor is partially discharged from the system 6, and part of it is returned to the dissolution tank 5. The rat...

Embodiment 3

[0038] The purity of 2,6-NDCA is 98.5%, the concentration of the slurry produced by the crude 2,6-NDCA in the mixing step is 12%, the temperature in the dissolution tank A is maintained at 350°C and 17MPa, and the dissolved slurry passes sequentially Crystallization unit, each crystallization process lasts 60 minutes, use 5 crystallization units in series to carry out described process, under the situation of 5 crystallization units in series, their temperature and pressure are respectively set as: their temperature and The pressure is set as: 270°C-285°C and 6.5-9MPa in the first crystallization unit, 250°C-265°C and 4.5-6.5MPa in the second crystallization unit, 235°C-250°C and 3.5-6.5MPa in the third crystallization unit 4.5MPa, 220°C-235°C and 2.5-3.5MPa in the fourth crystallization unit and 200°C-220°C and 2-2.5MPa in the fifth crystallization unit, after crystallization, the product and mother liquor are obtained through the solid-liquid separation unit, the mother liquo...

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Abstract

The invention provides a kind of high-purity 2,6 naphthalene dicarboxylic acid production method, comprises the following steps: (1) thick 2,6 naphthalene dicarboxylic acid is mixed with water, forms thick 2,6 naphthalene dicarboxylic acid slurry, (2) Heating the crude 2,6-naphthalene dicarboxylic acid slurry to 300°C-375°C, 8MPa-22MPa subcritical state; (3) cooling and crystallizing the dissolved 2,6-naphthalene dicarboxylic acid, (4) cooling crystallization The 2,6-naphthalene dicarboxylic acid slurry is subjected to solid-liquid separation to obtain high-purity 2,6-naphthalene dicarboxylic acid product; The problem of high circulation volume and high energy consumption.

Description

technical field [0001] The invention relates to a production method of high-purity 2,6-naphthalene dicarboxylic acid. Background technique [0002] Polyethylene terephthalate (PET), an industrial polyester material, is widely used in the manufacture of polyester fibers, bottles and film products due to its excellent performance and affordable price, covering chemical fiber, packaging, electronic appliances, medical Health, construction, auto parts and other fields. Although engineering plastic grade PET is resistant to organic solvents and has good weather resistance. But the disadvantages are slow crystallization rate, difficult molding process, high molding temperature, long production cycle and poor impact performance. Commonly found in mineral water bottles, carbonated beverage bottles, etc., it is easily deformed when the temperature reaches 70°C, and substances harmful to the human body are dissolved. After 10 months of use, No. 1 plastic (PET) may release the carci...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C51/43C07C63/38
CPCC07C51/43C07C63/38
Inventor 王清立陈亮钟思青顾军民
Owner CHINA PETROLEUM & CHEM CORP
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