A kind of single column heterogeneous phase azeotropic rectification separates the method of aniline and ethylene glycol azeotrope

Abstract

The present invention relates to a method for single tower heterogeneous azeotropic rectification separation of aniline and ethylene glycol. According to the method, cyclohexane is used as an azeotropic agent, is introduced into the upper portion of an azeotropic rectification tower, and completely contacts an aniline and ethylene glycol azeotrope entering from the middle portion of the tower, the high purity product aniline is extracted from the tower bottom, the heterogeneous azeotrope formed from cyclohexane and ethylene glycol is distilled off from the tower top, the tower top steam is firstly used as a heat source so as to pre-heat the raw material through a heat integration process, then the tower top steam is condensed through an auxiliary condenser, the condensed tower top steam enters a phase separator so as to be subjected to phase separation, the middle-lower layer product ethylene glycol of the phase separator is directly extracted, and the upper layer cyclohexane returns to the azeotropic rectification tower so as to be recycled. According to the present invention, the problem that the aniline-ethylene glycol system forms the lowest azeotrope under the normal pressure so as to difficultly separate is solved, the azeotrope is separated by using the single tower, the heat integration is achieved, and the method has advantages of low energy consumption, high product yield, simple process, and the like.

Description

【Technical field】 [0001] The invention belongs to the field of separation and purification in the chemical industry, and in particular relates to a single-tower heterogeneous azeotropic rectification method for separating aniline and ethylene glycol azeotrope. 【Background technique】 [0002] Aniline is a compound formed by replacing a hydrogen atom in benzene molecule with an amino group. Its physical properties are colorless or slightly yellow oily liquid with a strong odor. Its chemical properties are basic and can be combined with hydrochloric acid to form hydrochloride. Synthesize sulfate with sulfate. Aniline is one of the most important intermediates in the dye industry. It is used in dyeing nigrosine in the printing and dyeing industry; it is used in the production of many insecticides and fungicides in the pesticide industry, such as DDV, fenben, and toxachlor; aniline is An important raw material for rubber additives, used to manufacture anti-aging agents, etc.; it...

AI Technical Summary

Problems solved by technology

When synthesizing indole with aniline as a raw material, a large amount of ethylene glycol needs to be added, so a large amount of mixture of aniline and ethylene glycol will be produced in the post-treatment process, and aniline and ethylene glycol form an azeotrope under normal pressure. Distillation method is difficult to separate, in order to reduce production cost and reduce environmental pollution, it is necessary to effectively separate aniline and ethylene glycol

[0004] The patent (CN103396290A) discloses a process for separating ethylene glycol and 1,2-butanediol. The process uses toluene, ethylbenzene, xylene, etc. , the separation of 2-butanediol, the process has high energy consumption, the product purity is only 98%, and has not been realized in industrial application

[0005] Patent (CN105130755A) discloses a method for separating neopentyl glycol and ethylene glycol mixture. The method uses xylene as an entrainer, and utilizes a rectification tower and a solvent recovery tower to realize the separation of neopentyl glycol and ethylene glycol. The separation method of this process is complicated, the energy consumption is high, and the product purity is not high

[0006] Patent (CN106349107A) discloses a method for separating acetonitrile and triethylamine mixture and a device suitable for the method. The process uses n-hexane as an entrainer, and utilizes an azeotropic rectification tower and a stripping tower to realize the separation of acetonitrile and triethylamine. Separation of amines, the separation method of this process is complicated and the energy consumption is high

[0007] Literature (Azeotropic distillation separation of ethanol-isopropanol, Zhang Luan, etc., Progress in Chemical Industry, Volume 31, Issue 10, Pages 2187-2190, published on December 19, 2012) discloses a method for separating ethanol The process with isopropanol uses 1-hexene as an entrainer. Although a single tower is used to separate ethanol from isopropanol, this process only separates isopropanol and fails to separate ethanol. And the product purity is not high

[0008] There are many articles and patents on azeotropic distillation, but there is no published information on the separation of aniline and ethylene glycol azeotrope by azeotropic distillation

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