Method for producing hexane diacid and hexanediamine by using nylon-66 disaggregation

A technology of hexamethylenediamine and adipic acid, which is applied in chemical instruments and methods, amide preparation, recycling technology, etc., can solve the problems of energy consumption, insufficient production efficiency, and long time of acid hydrolysis with crude solution of hexamethylenediamine , to achieve the effect of reducing production cost, improving production efficiency and reducing risk

Inactive Publication Date: 2009-05-06
NINGBO UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] 1. The acid hydrolysis section takes a long time and uses phosphoric acid or phosphate as a catalyst, so the production efficiency is not high enough;
[0006] 2. Vacuum drying method is generally used to obtain dry CaSO 4 2H 2 The crude solution of O and hexamethylenediamine is very energy-consuming;
[0007] 3. CaSO generated in the whole production line 4 It is easy to scale on the wall of the reactor or the transfer pipeline, which seriously affects the production

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] A method for producing adipic acid and hexamethylenediamine by depolymerization of nylon-66, which comprises an acid hydrolysis section, a cooling crystallization section, a crude acid separation section, a recrystallization section, a neutralization section and a refining section, and the steps of each section are:

[0028] (1), acid hydrolysis section, add formic acid and water in the reactor, control the concentration of formic acid to be 5%, then add nylon-66 while heating, nylon-66 is dissolved, then add sulfuric acid, while keeping the pressure at 0.1~ React under the condition of 0.5MPa for 4 to 10 hours to obtain the acid solution;

[0029] (2), crude acid separation section and cooling crystallization section, the acid hydrolysis solution enters the cooling crystallization section through a coarse filter to carry out cooling crystallization, and then separates to obtain thick adipic acid crystals and hexamethylenediamine sulfate solution;

[0030] (3), refining...

Embodiment 2

[0036] A method for producing adipic acid and hexamethylenediamine by depolymerization of nylon-66, which comprises an acid hydrolysis section, a cooling crystallization section, a crude acid separation section, a recrystallization section, a neutralization section and a refining section, and the steps of each section are:

[0037] (1), acid hydrolysis section, add formic acid and water in the reaction kettle, control the concentration of formic acid to be 25%, then add nylon-66 while heating, nylon-66 is dissolved, then add sulfuric acid, while keeping the pressure at 0.1~ React under the condition of 0.5MPa for 4 to 10 hours to obtain the acid solution;

[0038] (2), crude acid separation section and cooling crystallization section, the acid hydrolysis solution enters the cooling crystallization section through a coarse filter to carry out cooling crystallization, and then separates to obtain thick adipic acid crystals and hexamethylenediamine sulfate solution;

[0039] (3), r...

Embodiment 3

[0045] A method for producing adipic acid and hexamethylenediamine by depolymerization of nylon-66, which comprises an acid hydrolysis section, a cooling crystallization section, a crude acid separation section, a recrystallization section, a neutralization section and a refining section, and the steps of each section are:

[0046] (1), acid hydrolysis section, add formic acid and water in the reactor, control the concentration of formic acid to be 1%, then add nylon-66 while heating, nylon-66 is dissolved, then add sulfuric acid, while keeping the pressure at 0.1~ React under the condition of 0.5MPa for 4 to 10 hours to obtain the acid solution;

[0047] (2), crude acid separation section and cooling crystallization section, the acid hydrolysis solution enters the cooling crystallization section through a coarse filter to carry out cooling crystallization, and then separates to obtain thick adipic acid crystals and hexamethylenediamine sulfate solution;

[0048] (3), refining...

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PUM

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Abstract

The invention relates to a method for producing hexanedioic acid and hexamethylene diamine by using nylon-66 to depolymerize, which is characterized by comprising the following steps: adding formylic acid and water into a reaction kettle, heating the mixture and adding the nylon-66 into the mixture at the same time, dissolving the nylon-66, adding sulphuric acid into the mixture, making the mixture react for 4 to 10 hours under the condition of keeping pressure intensity between 0.1 and 0.5MPa, so as to obtain acid hydrolysis solution; filtering obtained wet CaSO4.2H2O, and then obtaining dry CaSO4.2H2O and hexamethylene diamine solution by adopting a drying method; and adding Na3PO4 in the production process to prevent CaSO4 from scaling. By adopting the technique, the method can improve production efficiency, reduces even does not use phosphoric acid or phosphate, reduces production cost, improves recovery rate of the hexamethylene diamine, eliminates scaling in the production process, and reduces risk in the running process of equipment.

Description

technical field [0001] The invention relates to a method for producing adipic acid and hexamethylenediamine by depolymerization of nylon-66, in particular to a method for producing adipic acid and hexamethylenediamine by depolymerization of nylon-66 suitable for large-scale industrial production. Background technique [0002] Nylon-66 is a resin formed by polycondensation of adipic acid and hexamethylenediamine. During its synthesis and spinning process, unqualified products and scraps such as waste silk, short silk and miscellaneous scraps will be produced. In addition, various nylon products are difficult to dispose of after being used, which not only causes waste, but also pollutes the environment. new pollution. Therefore, recycling waste nylon-66 has significant economic and social benefits. [0003] At present, there are mainly some methods of nylon recycling: melt granulation regeneration; chemical recycling; energy recovery; landfill treatment, etc. However, due t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C211/12C07C209/62C07C51/06C07C55/14C08J11/10
CPCY02W30/62
Inventor 魏丹毅张振民王邃孙利民郭智勇
Owner NINGBO UNIV
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