CS249336B1 - Method of separation of collidine fraction components - Google Patents

Abstract

The solution relates to a method for separating the components of the collidine fraction of hard coal, brown coal, petroleum or synthetic origin by combining azeotropic distillation with water and simple rectification. Both rectifications are carried out on a device with an efficiency of over 50 theoretical plates, preferably 80 theoretical plates. Azeotropic distillation is carried out at a mass ratio of the components of the collidine fraction and water in the distillation head in the range of 1:1 to 1:10, preferably 2:3 to 1:4. During azeotropic distillation with water, a binary mixture of 2,4,6- and 2,3,6-trimethylpyridinefl with water and an azeotropic mixture of 3,5-dimethylpyridine with water are obtained. During simple rectification, a binary mixture of 2,4,6-trimethylpyridine with water and 3,5-dimethylpyridine and 2,3,6-trimethylpyridine is obtained. A mixture of trimethylpyridines from azeotropic distillation can be separated into pure components by simple rectification. A mixture of 2,4,6-trimethylpyridine with 3,5-dimethylpyridine from simple rectification can be separated into pure components by azeotropic distillation with water. The intermediate fraction and water separated from the azeotropic mixtures can be used in the next distillation batch, or circulated in the case of continuous distillation.

Description

(54) Method of separation of collidine fraction components

The invention relates to a method for separating the components of the collidine fraction of coal, lignite, petroleum or synthetic origin by combining azeotropic distillation with water and free of rectification. Both rectifications are carried out on equipment having an efficiency of over 50 theoretical plates, preferably 80 theoretical plates. The azeotropic distillation is carried out at a weight ratio of the collidine fraction and water components in the distillation batch in the range of 1: 1 to 1:10, preferably 2: 3 to 1: 4. Azeotropic distillation with water yields a binary mixture

2,4,6- and 2,3,6-trimethylpyridine with water and an azeotropic mixture of 3,5-dimethylpyridine with water. Simple rectification yields a binary mixture of 2,4,6-trimethylpyridine with water and 3,5-dimethylpyridine and 2,3,6-trimethylpyridine. The mixture of trimethylpyridines from azeotropic distillation can be separated into pure components by simple rectification. A mixture of 2,4,6-trimethylpyridine with 3,5-dimethylpyridine from simple rectification can be separated into the pure components of azeotropic by distillation with water. The intermediate fraction and the water separated from the azeotropic mixtures can be used in another distillation batch or circulated in the case of continuous distillation.

SUMMARY OF THE INVENTION The present invention provides a method for separating the components of the collline fraction of coal, lignite, petroleum or synthetic origin.

The collidine fraction is a mixture of pyridine bases boiling in the temperature range of 168-175 ° C in which isomeric trimethylpyridines predominate. The average composition of the colloline black coal tar fraction is 45% 2,4,6-trimethylpyridine, 17% 2,3,6-trimethylpyridine, 10% 3,5-dimethylpyridine, 6% 3,4-dimethylpyrldine, 7% aniline 10% isomeric ethylmethylpyridines and 5% below boiling pyridine homologs. In particular, the ability to selectively form crystalline salts, adducts, complexes and clathrates with inorganic and organic compounds is utilized to isolate the components of the colloquine fraction. The isolation also sometimes involves the reaction of bases with amides, aldehydes, their oxidation to N-oxides and the like. For example, 2,4,6-trimethylpyridine can be separated from the collidine fraction using hydrochloric acid / US Pat. 2,426,442), phosphorous (USSR Pat > 149,784), with o-cresol (Germany Pat. No. 1,245,963), calcium chloride complex (PI * Pat. 56 971 /.

by reaction with formamide / NSR Pat. In all cases, 2,4, (trimethylpyridine in a purity of about 95 S and in a yield of 50 to 60% of the raw collolidine fraction) can be obtained. auxiliary substances and the generation of waste water, the disposal and treatment of which is expensive.

Most of the above drawbacks are solved by the method of separating the components of the collidine fraction of the present invention. Its essence is the combination of azeotropic distillation with water on an efficient rectification apparatus with simple rectification of the collidine fraction on the same apparatus.

The efficiency of the still should be above 50 theoretical plates, preferably 80 theoretical plates. Azeotropic rectification is carried out at the mass ratio of the collidine fraction. % and water in the distillation batch in the range of 1: 1 to 1:10, preferably 2: 3 to 1: 4. The components of the collidine fraction are separated by distillation as azeotropic mixtures with water. The main fraction is an azeotropic mixture of water and a binary mixture of 2,4,6-trimethylpyridine with 2,3,6-trimethylpyridinera and an azeotropic mixture of water with 3,5-dimethylpyridine. The intermediate fractionation of the two azeotropic mixtures and the water separated from the main fractions can be used in another distillation batch, or circulated in the case of continuous distillation. By simply rectifying the components of the collidine fraction, a binary mixture of 2,4,6-trimethylpyridine with 3,5-dimethylpyridine is obtained as the main fraction, and a high percentage of 2,3,6-trimethylpyridine concentrate is obtained as a side fraction. By combining both rectification procedures, both isomeric trimethylpyridines and 3,5-dimethylpyridine can be obtained in high purity and correspondingly high yield.

The main advantages of this process are to obtain both 2,4,6- and 2,3,6-trimethylpyridine and 3,5-dimethylpyridine in high yield and corresponding to high purity by a combination of two operations which are technologically and economically significantly more advantageous than the processes used hitherto. This process is also advantageous from the point of view of waste, since, in contrast to the previous processes, no harmful or difficult-to-treat and liquid-free waste is produced in this case. The individual intermediate fractions from azeotropic and simple rectification can be combined and recycled to another distillation batch, as well as water separated from the azeotropic mixtures. Thus, this method of separating the components of the collidine fraction meets the requirements of waste-free technology.

2,4,6-trimethylpyridine can be obtained in this manner in a yield of 65% and a purity of over 95%; 2,3,6-trimethylpyridine in a yield of more than 65% and a purity of more than 97%; 3,5-dimethylpyridine in a yield of 70% and a purity of more than 96%. The yields of the individual products are increased when circulating through the fractions.

Particular embodiments of the separation of the collidine fraction components of the invention are described in the following examples.

He did

Collidine fraction boiling in the range of 168-175 ° C, containing 47,2% 2,4,6-trimethylpyridine, 25,6 and 2,3,6-trimethylpyridine, 9.5% 3, 5'-dimethylpyridine, 7,3 % -ethylpyridine and 2-ethyl-4-methylpyridine, 3.7% 3,4-dimethylpyridine, 5.8% lower boiling pyridine homologues and 0.9% aniline were mixed with water in a 1: 4 weight ratio. The mixture was rectified at atmospheric pressure on a distillation apparatus of 80 theoretical plates at a reflux ratio of 80: 1. After separation of the opening containing the lower-boiling pyridine homologues, a mixture of water with trimethylpyridines containing 60 to 65% water was collected. After dewatering of this fraction, a mixture was obtained containing 62.4% 2,4,6-trimethylpyridine, 27.8% 2,3,6-trimethylpyridine and 9.8% other bases in which 2-ethyl-4-methylpyridine predominated . 95.5% of 2,4,6- and 78.3% of 2,3,6-trimethylpyridine from the starting material were concentrated into this fraction. The trimethylpyridine mixture was then repeatedly rectified on the same apparatus under the same conditions without the addition of water. Two major fractions were obtained, namely 97.5% 2,4,6-trimethylpyridine in 68% yield on the starting collidine fraction and 98.7% 2,3,6-trimethylpyridine in 61% yield on the starting fraction.

Example 2

The collidine fraction / water mixture of Example 1 was further azeotroped with water after separation of the trimethylpyridine mixture. A mixture of 3,5-dimethylpyridine with 70% water was obtained.

After dewatering, 97% 3,5-dimethylpyridine was obtained in 70% yield on the starting fraction.

Example 3

The collidine fraction specified in Example 1 was rectified on a 70 theoretical plate distillation apparatus at a reflux ratio of 70: 1. After separation of the opening, a mixture containing 85.2% 2,4,6-trimethylpyridine, 12.0% 3,5-dimethylpyridine and 3.8% other pyridine homologs was collected. To this mixture was concentrated 81.1% 2,4,6-trimethylpyridine and 78.2% 3,5-dimethylpyridine from the starting material. Water was added to the mixture in a weight ratio of 2: 3.5 and the resulting mixture was repeatedly rectified on the same apparatus and under the same conditions. A mixture of 2,4,6-trimethylpyridine with 65% water was collected as the main fraction. After dewatering, 98% 2,4,6-trimethylpyridine was obtained in 63% yield on the starting collidine fraction. A mixture of 3,5-dimethylpyridine with 70% water was collected as a second crop. After dewatering, 95% of 3,5-dimethylpyridine was obtained in 61% yield on the starting material.

Example 4

The collidine fraction of Example 1 rectified according to Example 3 was after separation of the mixture

2,4,6-trimethylpyridine and 3,5-dimethylpyridine further rectified. Between 172.5 and 173.0 ° C, 95% 2,3,6-trimethylpyridine was obtained in 40% yield over the starting fraction.

Claims (4)

SUBJECT OF THE INVENTION CLAIMS 1. A method for separating the components of the colloline fraction of coal, lignite, petroleum or synthetic origin, characterized by combining azeotropic distillation with water of simple rectification, both operations being carried out on equipment with efficiency above 50 theoretical plates, preferably 80 theoretical plates, and azeotropic distillation. The reaction is carried out at a weight ratio of bases to water of from 1: 1 to 1:10, preferably from 2: 3 to 1: 4. 2. The process of claim 1, wherein the components of the collidine fraction are first distilled azeotropically with water to form the individual components or their binary mixtures, and after dewatering, the binary mixtures are repeatedly rectified without the addition of water. 3. The process according to claim 1, wherein the components of the collidine fraction are first rectified without the addition of water and the resulting binary base mixtures are repeatedly distilled with the addition of water. 4. A method according to claim 1, 2 and 3, characterized in that the intermediate fraction and the water separated from the azeotropic mixtures are used in another distillation batch or circulated in the case of continuous operation.