CN108017551B

CN108017551B - Method for recovering dimethylethanolamine from hydrazine reaction solution

Info

Publication number: CN108017551B
Application number: CN201711354893.XA
Authority: CN
Inventors: 陈骏; 周龙达; 杨常桥
Original assignee: Shanghai Shisi Chemical Product Co ltd
Current assignee: Shanghai Shisi Chemical Product Co ltd
Priority date: 2017-12-15
Filing date: 2017-12-15
Publication date: 2020-06-05
Anticipated expiration: 2037-12-15
Also published as: CN108017551A

Abstract

The invention discloses a method for recovering dimethylethanolamine from hydrazine reaction liquid, which is characterized in that benzene is added into the hydrazine reaction liquid to extract dimethylethanolamine, then the benzene and dimethylethanolamine are separated by adopting a method of combining distillation and rectification, and the high-purity dimethylethanolamine is recovered. The invention adopts benzene extraction, simple distillation and rectification to effectively recover the dimethylethanolamine in the hydrazine reaction mother liquor, and has low energy consumption in the recovery process, high purity of the recovered dimethylethanolamine and no influence on the hydrazine synthesis reaction due to repeated use.

Description

Method for recovering dimethylethanolamine from hydrazine reaction solution

Technical Field

The invention belongs to the field of fine chemical engineering, and particularly relates to a method for recovering dimethylethanolamine from a hydrazine reaction solution.

Background

In the conventional organic solvent purification process, a distillation method, particularly a rectification method is mainly adopted for removing water, and the method of collecting fractions by controlling the reflux ratio and the top temperature control improves the content of the organic solvent and reduces the water in the organic solvent. Some solvents also have been treated by adding a water absorbent (e.g., solid sodium hydroxide or concentrated sulfuric acid) to remove traces of water from the organic solvent, and some solvents (e.g., benzene) have been dehydrated in an azeotropic form. However, these methods are only suitable for removing a trace amount of water from a high-concentration organic solvent, or for recovering a solvent from a relatively single solution and containing a very small amount of water, and for recovering a dimethylethanolamine solvent from a mother liquor containing more than 10% of water in a hydrazinization reaction, these methods cannot be used.

For the recovery of dimethylethanolamine solvent from the mother liquor of the hydrazidation reaction, many attempts have been made for a long time by using various methods, but the results are not satisfactory. Dimethyl ethanolamine is recovered by chloroform solvent, NaOH is added to adjust the pH value, the production operation is not complicated, and the raw material cost is increased. Secondly, hydrazine hydrate in the hydrazine reaction mother liquor is dissolved in the trichloromethane, and the hydrazine hydrate is high in safety risk when the trichloromethane and the dimethylethanolamine are separated by high-temperature rectification, so that the hydrazine hydrate is not beneficial to safe production operation.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for recovering dimethylethanolamine from a hydrazine reaction solution aiming at the difficult problem of recovering dimethylethanolamine solvent from the existing hydrazine reaction mother solution.

The technical problem to be solved by the invention can be realized by the following technical scheme:

a method for recovering dimethylethanolamine from hydrazine reaction liquid is characterized in that benzene is added into the hydrazine reaction liquid to extract dimethylethanolamine, then the benzene and dimethylethanolamine are separated by adopting a method of combining distillation and rectification, and the dimethylethanolamine with high purity is recovered.

The method comprises the following specific steps: adding an extractant benzene into the hydrazine reaction solution, heating to 55-65 ℃, stirring, preserving heat for 0.5 hour, standing and then splitting phases; distilling the upper organic phase; the organic phase is distilled under normal pressure to 125-130 ℃; rectifying the collected fraction, and collecting the fraction at 130-134 ℃, namely the dimethylethanolamine solvent.

In a preferred embodiment of the invention, the mass ratio of the hydrazine reaction liquid to the extracting agent is 1: 0.8.

In a preferred embodiment of the invention, the resting time is more than 0.5 hour.

The invention adopts benzene extraction, simple distillation and rectification to effectively recover the dimethylethanolamine in the hydrazine reaction mother liquor, and has low energy consumption in the recovery process, high purity of the recovered dimethylethanolamine and no influence on the hydrazine synthesis reaction due to repeated use. The invention has unique advantages, which are mainly embodied as follows: firstly, hydrazine hydrate is insoluble in benzene, and almost no hydrazine hydrate is contained in the extracted benzene solution, so that the risk of rectifying hydrazine hydrate at high temperature does not exist; secondly, NaOH is not needed to adjust the pH value in the benzene extraction, so that the complexity of the operation process is reduced, and the effect of saving raw materials is achieved; thirdly, the dimethylethanolamine extracted from the benzene contains no water-soluble impurities basically, and the dimethylethanolamine obtained after rectification has higher purity and is more favorable for being repeatedly used in hydrazine synthesis reaction; and fourthly, benzene is used as a solvent to be easier to separate in the extraction process. In a word, the production operation is safe, the purity of the recovered dimethylethanolamine is high, and the operation is simple.

For example: the composition of a certain hydrazidation reaction mother liquor is as follows: 42% of dimethylethanolamine; 5% of hydrazine hydrate; dimethylethanolamine hydrochloride 30%; water content is 13 percent; other impurities 10%;

adding an extractant benzene into the mother liquor according to the mass ratio of 1:0.8, heating to 55-65 ℃, stirring, keeping the temperature for about 0.5 hour, standing for about 0.5 hour, and then carrying out phase separation; distilling the upper organic phase; the organic phase is simply distilled to 125-130 ℃ under normal pressure; the collected fraction is rectified again, the fraction at the temperature of 130-134 ℃ is collected, and finally 0.4 ton of dimethylethanolamine solvent can be recovered in each ton of mother liquor.

The content of the recovered dimethylethanolamine is more than 98 percent, the benzene residue is less than 0.8 percent, and the water content is less than 0.5 percent; the remainder being the product of the hydrazinization reaction.

Detailed Description

Example 1

2310Kg of benzene is added into a hydrazine reaction mother liquor, and extraction is carried out twice under the condition of heating to 55.6-57.8 ℃ to obtain an extraction liquid. The extract liquid is simply distilled at the temperature of 128-130 ℃, the fraction at the temperature of 132.2-133.4 ℃ is collected, and then the collected fraction is rectified, and 940Kg of recovered solvent is finally obtained. The quality index of benzene is 0.72 percent; 98.54 percent of dimethylethanolamine; 0.4 percent of water.

Example 2

Adding 1800Kg of benzene into 2300Kg of hydrazine reaction mother liquor, and extracting twice under the condition of heating to 55.5-58.1 ℃ to obtain extract liquor. The extract liquid is simply distilled at the temperature of 128-130 ℃, collected at the temperature of 132.0-133.5 ℃, and then the collected fraction is rectified to finally obtain 920Kg of recovered solvent. The quality index of benzene is 0.72 percent; 98.54 percent of dimethylethanolamine; 0.5 percent of water.

Example 3

2320Kg of benzene is added into a certain hydrazinization reaction mother liquor, and the mixture is extracted twice under the condition of heating to 55.4-57.9 ℃ to obtain extract liquor. The extraction liquid is simply distilled, the fraction is collected at the temperature of 128-130 ℃, then the distillation is carried out, and finally the fraction at the temperature of 132.1-133.5 ℃ is collected to obtain 940Kg of recovered dimethylethanolamine solvent, the quality index of which is 0.668 percent of benzene; 98.82% of dimethylethanolamine; 0.3 percent of water.

Claims

1. A method for recovering dimethylethanolamine from a hydrazine reaction solution is characterized in that benzene is added into the hydrazine reaction solution to extract dimethylethanolamine, then the benzene and the dimethylethanolamine are separated by adopting a method of combining distillation and rectification, and the dimethylethanolamine with high purity is recovered;

2. The method for recovering dimethylethanolamine from a hydrazinization reaction solution according to claim 1, wherein the mass ratio of the hydrazinization reaction solution to the extracting agent is 1: 0.8.

3. The method for recovering dimethylethanolamine from a hydrazinization reaction solution according to claim 1, wherein the standing time is more than 0.5 hour.