Method for preparing high-purity triethylene diamine

Abstract

The invention discloses a method for producing high-purity triethylene diamine, which comprises the following steps: using a triethylene diamine reaction liquid from which low boiling point substances (including ammonia gas, water, ethylene diamine, diethylenediamine and the like) are removed as a raw material for rectification, adding C2-C5 hydroxylamine compounds which contain branched chains (methyl or ethyl groups) or contain no branched chains and account for 40-120% of the weight of the triethylene diamine reaction liquid, and rectifying on a rectifying tower to obtain a high-purity triethylene diamine solution, wherein the obtained azeotropic solution can be directly used as a catalyst, the concentration of the solution can be changed as required by regulating vacuum pressure, and the solution can be subject to cooling crystallization to separate out triethylene diamine the purity of which is higher than 99.9%. The invention has the characteristics of simple operating process and high purity of the purified product.

Description

technical field [0001] The invention belongs to the technical field of separation and purification of fine chemicals, and relates to a method for preparing high-purity triethylenediamine by subsequent separation and purification of a reaction solution synthesized from triethylenediamine using ethylenediamine or ethanolamine as a raw material. Background technique [0002] Triethylenediamine is a foaming agent for the production of polyurethane soft, semi-rigid, and rigid foams, and is also used in ethylene polymerization catalysts, coatings, and plastic products. Its derivatives can be used in petroleum additives, corrosion inhibitors, emulsifiers, etc. [0003] At present, the main raw materials for the preparation of triethylenediamine are N-hydroxyethylpiperazine, ethylenediamine, ethanolamine, piperazine, etc. Triethylenediamine itself has a melting point of 159.8°C and a boiling point of 174°C, and the temperature range in which it exists in a liquid state is only 14.2...

AI Technical Summary

Problems solved by technology

[0003] At present, the main raw materials for the preparation of triethylenediamine are N-hydroxyethylpiperazine, ethylenediamine, ethanolamine, piperazine, etc. The melting point of triethylenediamine itself is 159.8 °C, the boiling point is 174 °C, and the temperature range in the liquid state is only 14.2 °C, which makes triethylenediamine very easy to crystallize and block the pipeline during the rectification process, thus increasing the difficulty of distillation

Most patents prepare pure product solutions by quenching triethylenediamine. For example, US6627756B1 and US6552194B2 respectively disclose quenching and purification methods for triethylenediamine. However, these methods require the evaporator to be heated or kept warm, and the initial The purity of the obtained product is not high, and it needs to be further vaporized and condensed in a solvent with a high boiling point. The equipment investment is high, the energy consumption is large, and the process is cumbersome