Method for preparing terephthalic acid and p-phenylenediamine by degrading p-aramid fibers

A technology of terephthalic acid and p-phenylenediamine, which is applied in chemical instruments and methods, amide preparation, carboxylate preparation, etc., to achieve the effects of controllable degradation and mild reaction process conditions

Active Publication Date: 2019-12-13
SHANXI INST OF COAL CHEM CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The invention provides a method for preparing terephthalic acid and p-phenylenediamine by degrading para-aramid to solve the technical problem of para-aramid recycling

Method used

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  • Method for preparing terephthalic acid and p-phenylenediamine by degrading p-aramid fibers
  • Method for preparing terephthalic acid and p-phenylenediamine by degrading p-aramid fibers
  • Method for preparing terephthalic acid and p-phenylenediamine by degrading p-aramid fibers

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Embodiment 1

[0027] In this embodiment, a method for degrading para-aramid fibers to prepare terephthalic acid and p-phenylenediamine comprises the following steps:

[0028] Step 1: Prepare reaction system I by mixing aluminum chloride and formic acid with catalyst mass fraction of 10%, mix para-aramid fiber and reaction system I at a mass ratio of 1:1 and add to the reactor, seal and put into homogeneous reaction The device was heated to 280°C and reacted for 36h. Cool to room temperature after the reaction, add deionized water to wash, filter to remove aluminum chloride and formic acid, and the reaction products are terephthalic acid and terephthalic acid derivatives. Aqueous potassium hydroxide solution is added to dissolve the potassium salt of terephthalic acid, and the solution of terephthalic diamide acyl derivative and potassium terephthalic acid is separated by filtration. Add hydrochloric acid to the potassium terephthalic acid solution to precipitate terephthalic acid, wash, fi...

Embodiment 2

[0032] In this embodiment, a method for degrading para-aramid fibers to prepare terephthalic acid and p-phenylenediamine comprises the following steps:

[0033] Step 1: Prepare reaction system Ⅰ by ferric chloride and acetic acid at 1% catalyst mass fraction, mix para-aramid fiber and reaction system Ⅰ at a mass ratio of 1:50 and add to the reactor, seal and put into homogeneous reaction The device was heated to 180°C and reacted for 1h. Cool to room temperature after the reaction, add deionized water to wash, filter to remove ferric chloride and acetic acid, and the reaction products are terephthalic acid and terephthalic acid derivatives. Aqueous sodium hydroxide solution was added to dissolve the sodium salt of terephthalic acid, and the solution of terephthalic diamide acyl derivative and sodium terephthalic acid was obtained by separating by filtration. Add hydrochloric acid to the sodium terephthalic acid solution to precipitate terephthalic acid, wash, filter and dry t...

Embodiment 3

[0037] In this embodiment, a method for degrading para-aramid fibers to prepare terephthalic acid and p-phenylenediamine comprises the following steps:

[0038] Step 1: Prepare reaction system I by preparing copper sulfate and propionic acid with a catalyst mass fraction of 30%, mix para-aramid fiber and reaction system I at a mass ratio of 1:100 and add to the reactor, seal it and put it into a homogeneous reaction The device was heated to 100°C and reacted for 72h. Cool to room temperature after the reaction, add deionized water to wash, filter to remove copper sulfate and propionic acid, and the reaction products are terephthalic acid and terephthalic acid derivatives. Lithium hydroxide aqueous solution was added to dissolve the lithium salt of terephthalic acid, and the solution of terephthalic diamide acyl derivative and lithium terephthalate was separated by filtration. Add hydrochloric acid to the lithium terephthalate salt solution to precipitate terephthalic acid, wa...

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Abstract

The invention belongs to the field of cycle utilization and recycling of waste high-molecular materials, and particularly relates to a method for preparing terephthalic acid and p-phenylenediamine bydegrading p-aramid fibers. The technical problem of recycling of p-aramid fibers is mainly solved. Amide bonds are selectively broken through metal ion coordination catalysis, and an exchange reactionof an organic carboxylic acid and the amide bonds is used to controllably degrade the p-aramid fibers in order to obtain terephthalic acid and a p-phenylenediamine acyl derivative. Terephthalic acidcan be separated firstly by utilizing the characteristics of water solubility and acidification precipitation of terephthalate; and then the p-phenylenediamine acyl derivative undergoes an alcoholysisreaction by using a strong base as a catalyst, and the p-phenylenediamine is precipitated through cooling crystallization. The method achieves controllable chemical degradation of the p-aramid fibersand recovery and preparation of the monomers terephthalic acid and p-phenylenediamine.

Description

technical field [0001] The invention belongs to the field of recycling and resource utilization of waste polymer materials, and in particular relates to a method for preparing terephthalic acid and p-phenylenediamine by degrading para-aramid fibers. Background technique [0002] Poly(p-phenylene terephthalamide) can be obtained by direct polycondensation of terephthalic acid and p-phenylenediamine, or by polycondensation of terephthaloyl chloride and p-phenylenediamine. It belongs to lyotropic liquid crystal polymer, which can be processed into fibers, called aramid 1414 or para-aramid, and the trade name of DuPont is Kevlar. At present, the main producers of aramid fibers in the world are DuPont Corporation of the United States and Teijin Corporation of Japan. The total aramid fiber production of the two companies accounts for about 79.1% of the global production capacity. In 2016, the global production capacity of para-aramid was about 81kt / a, and the combined production ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/06C07C63/28C07C51/02C07C63/26C07C209/62C07C209/84C07C211/55C07C231/12C07C233/80
CPCC07C51/02C07C51/06C07C209/62C07C209/84C07C231/12C07C233/80C07C63/28C07C63/26C07C211/55
Inventor 侯相林王玉琪田梓赏王英雄
Owner SHANXI INST OF COAL CHEM CHINESE ACAD OF SCI
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