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Method for preparing polymer-grade m-phenylenediamine through melt crystallization and recycling mother liquor

A m-phenylenediamine, melting and crystallization technology, applied in amino compound purification/separation, organic chemistry, etc., can solve the problems of high purification cost, large quality fluctuation, incomplete separation of mother liquor, etc., and achieve high crystallization yield and purification low cost effect

Pending Publication Date: 2022-03-29
四川北方红光特种化工有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, the gray product m-phenylenediamine is purified, and the finished product of polymer grade m-phenylenediamine can be obtained through solvent crystallization and distillation treatment, but this method needs to use a water-containing solvent, and if the water separation is not complete, it will seriously affect the shelf life of the product (easy to oxidize ), and the crystallization process belongs to layered solution crystallization, and the crystallization rate is not easy to control; in addition, the gray product m-phenylenediamine can also be purified by melting crystallization, but this method generally uses gravity to separate the crystal from the mother liquor, and the separated The mother liquor continues to crystallize, resulting in incomplete separation of the mother liquor during the separation process, severe intercrystalline packaging, large quality fluctuations, and high purification costs

Method used

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Examples

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Effect test

Embodiment 1

[0023] This example provides a method for preparing polymer-grade m-phenylenediamine by melt crystallization and resource utilization of mother liquor, including the following steps:

[0024] S1: After heating and melting the gray m-phenylenediamine, cool it down to 52°C at a rate of 2°C / min for primary crystallization. -5 MPa, vacuum constant temperature centrifugation at a constant temperature of 52°C, separate the mother liquor and send it back to the rectification process;

[0025] S2: The crystals separated in step S1 are heated and melted, and then cooled to 45°C at a rate of 1°C / min for secondary crystallization. -5 MPa, vacuum constant temperature centrifugation at a constant temperature of 45°C, the mother liquor is separated and returned to the rectification process, and the separated crystal is polymer grade m-phenylenediamine.

Embodiment 2

[0027] This example provides a method for preparing polymer-grade m-phenylenediamine by melt crystallization and resource utilization of mother liquor, including the following steps:

[0028] S1: Heat and melt the gray m-phenylenediamine, then cool down to 55°C at a rate of 1°C / min for primary crystallization, and crystallize for 60 minutes in a vacuum of 10 -5 MPa, vacuum constant temperature centrifugation at a constant temperature of 55°C, separate the mother liquor and send it back to the rectification process;

[0029] S2: The crystals separated in step S1 are heated and melted, and then cooled to 50°C at a rate of 0.5°C / min for secondary crystallization. -5 MPa, vacuum constant temperature centrifugation at a constant temperature of 50°C, the mother liquor is separated and returned to the rectification process, and the separated crystal is polymer grade m-phenylenediamine.

Embodiment 3

[0031] This example provides a method for preparing polymer-grade m-phenylenediamine by melt crystallization and resource utilization of mother liquor, including the following steps:

[0032] S1: After heating and melting the gray m-phenylenediamine, cool it down to 57°C at a rate of 0.1°C / min for primary crystallization. -6 MPa, vacuum constant temperature centrifugation at a constant temperature of 57°C, separate the mother liquor and send it back to the rectification process;

[0033] S2: The crystals separated in step S1 are heated and melted, and then cooled to 50°C at a rate of 0.1°C / min for secondary crystallization. -6 MPa, vacuum constant temperature centrifugation at a constant temperature of 50°C, the mother liquor is separated and returned to the rectification process, and the separated crystal is polymer grade m-phenylenediamine.

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PUM

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Abstract

The invention provides a method for preparing polymer-grade m-phenylenediamine through melt crystallization and recycling mother liquor, and relates to the technical field of m-phenylenediamine production. A method for preparing polymer-grade m-phenylenediamine through melt crystallization and recycling mother liquor comprises the following steps that S1, ash m-phenylenediamine is heated and melted and then cooled to the temperature T1 at the speed of v1 for crystallization, vacuum constant-temperature centrifugation is conducted after crystallization is conducted for t1, mother liquor is separated out and sent back to a rectification procedure, and crystals separated out are the polymer-grade m-phenylenediamine. According to the method, crystals and mother liquor can be separated thoroughly, the purity of the purified m-phenylenediamine is high, and the purification cost is low.

Description

technical field [0001] The invention relates to the technical field of m-phenylenediamine production, in particular to a method for preparing polymer-grade m-phenylenediamine by melt crystallization and resource utilization of mother liquor. Background technique [0002] The preparation of a polymer grade m-phenylenediamine is to use mixed dinitrobenzene as raw material, add alcohol solvent and catalyst, carry out catalytic hydrogenation to generate mixed diaminobenzene reducing liquid, and then go through dealcoholization, dehydration, decoking and rectification Obtain gray product m-phenylenediamine. [0003] At present, the gray product m-phenylenediamine is purified, and the finished product of polymer grade m-phenylenediamine can be obtained through solvent crystallization and distillation treatment, but this method needs to use a water-containing solvent, and if the water separation is not complete, it will seriously affect the shelf life of the product (easy to oxidiz...

Claims

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Application Information

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IPC IPC(8): C07C209/86C07C211/51
CPCC07C209/86C07C211/51
Inventor 黄清武向勇宁萍杜成平张建琴刘晓燕冯刚蒲祖伦
Owner 四川北方红光特种化工有限公司
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