SU645951A1 - Method of separating polyethylenepolyamines - Google Patents

Description

This invention relates to an improved process for the isolation of polyethylben amines (PEG1L) from the reaction mixture resulting from the preparation of ethylene diamine (EDA) or NEPA, which is a valuable raw material for the production of pre-chemicals, plastics, and oil additives.

The patent and technical literature broadly describes the various methods for separating HGAP from the reaction mixture resulting from the preparation of EDA or PEPA after neutralization, which contains water, sodium chloride, excess alkali, EDA, piperazine, diztilentiriamine and others, PEPA.

In particular, methods are known for separating PEP with an organic solution; 1 body (1) or by treating the reaction mixture with ammonia and then dispersing a layer of amines and salts 2.

The closest to the invention in its technical nature is a method for separating PEPA from the reaction mixture containing aqueous solutions of salts and alkalis by distillation with water vapor at 120-180 ° C. With this ED with

part of PEP is collected as distlate. The bottom residue, containing a suspension of sodium chloride in water and PEP, is fed to a centrifuge, where the solid phase is separated from the liquid. The liquid phase is recycled, the solid phase is rinsed with water, the salt is sent for recycling, and the wash water is recycled to the distiller 3.

However, this known method has a significant drawback - large losses (up to 50%) of PEPA together with sodium chloride and bottom liquid.

The invention is more complete extraction of PEP.

The goal is achieved by the method of separating PEPA from the reaction mixture containing aqueous solutions of salts and alkalis by distillation, which means that the disagglometion is carried out in two stages, and first of all the water from the reaction mixture is removed from E.L. Q and low-boiling polyamines at atmospheric pressure and temperature 100-130 ° C until the concentration of the solid phase in the residue is 20-70% by weight, and then the distillation is carried out at 36 pressure 50-760 mm Hg. and a temperature of {00-ISOC before the suspension in the bottoms of the suspension of salts in anhydrous PEPA, followed by separation of PEPA from salts. The yield of PEP reaches 99.2%. About the difference between 1 body and 1 sign of the proposed method of separating PEP is that the distillation is carried out in two stages, first at atmospheric pressure and a temperature of 100-130 and then at a pressure of 50-760 mm Hg. and a temperature of 100-130 ° C. The technology of the method is as follows (see drawing). The reaction mixture is fed to the distillation in the distiller 1, operating at atmospheric pressure, to separate the bulk of the water and part of the EDA as an azeotrope with water at a bottom temperature of 100-130 ° C until the sodium chloride content in the vat residue is no more than wt.% (the ratio of the solid phase to the cage in the cube is not more than 2), which allows one to maintain a high mobility of the bottoms liquid, which enters the separator 2, where the liquid phase is separated from the salt crystals. To increase the degree of salt separation, the bottoms upstream of the air separator are up to 20-80 ° C. The salt is rinsed with water and; stews are freed from sorbed PEPA and sent to calcining. Industrial water enters the setter 1. The mother liquor from separator 2, containing water, sodium chloride and other salts, EDA, high boiling PES, goes to the final dehydration to the distiller 3, operating At a pressure of 50–760 mm Hg, in which at a cube temperature. 100-130 ° C. The remainder of the water is distilled off with some EDA and PEPA. Distillers from distillers 1 and 3 are fed to the extraction of EDA by a known method. The bottom residue from distiller 3, containing a suspension of salt in PEP, is fed to a separator 4, where the salts are separated from PEP. Salt from a separator 4 is fed to calcining, and PEP, to rectification to obtain individual amines (diethylenetriamine, amyoethylpiperazine, etc.). Example 1. A mixture of the composition,% (kg) is fed to the distiller 1 and distiller 1:

105-110 C and atmospheric pressure take a mixture of composition,% (KG):

Only 100 (47.2)

served in separator 4, where the salt of the composition is separated,% (kg):

Sodium Chloride 98.2 (17.0)

PEPA1,8 (0,3)

Only 100 (17.3)

 comes to calcining and recycling.

The mother liquor from separator 4, containing,% (kg): Total 100 (671) Kubov residue of composition,% (kg): Water Caustic soda Sodium carbonate Sodium chloride EDA PEPA Total 1SU (329) is given to separator 2, where solid is separated salt after washing,% (kg): Sodium chloride Carbonic acid sodium Sodium hydroxide Water Total 100 (220) Salt is directed to calcining and electrolysis. exact solution of composition,% (kg): Sodium chloride EDA A total of 100 is given in the distiller 3, where at a pressure of 0-300 mm Hg. and the temperature of the cube 105-110 ° C chase the distillate composition, (kg): Water71.4 (54.8) EDA26.0 (20.0) PEPA2.6 (2.0) Total 100 (76.8) stil You from distillers 1 and 3 are fed to the ED in a known manner. VAT residue from the distiller 3 composition, (kg): Chloride

(0,2)

0.7

(20,0)

66.2

(10.0)

33.1

(30.2)

Only 100 is fed to the rectification of PEPA.

EXAMPLE 2 An initial mixture, analogous to example 1, is fed to a distillation, where at atmospheric pressure and the highest possible temperature (180 ° C) the mixture is taken as a distillate,% (kg): Water

which comes to incineration, since the dachie most of its return to recycling for distillation will lead to an increase in temperature above 180 ° С and decomposition, as well as to the osmolesion of the cube.

From the above examples it is clear that the proposed method of exit. PEPA is 99.2%, while by a known method only about 50%.