SU925929A1 - Method for separating azeotropic mixture of diethylene glycol and mono c1-c2-alkylester of triethylene glycol - Google Patents

Description

(5) METHOD FOR SEPARATION OF AZETROPIC MIXTURE OF DIETHYLENE GLYCOL AND MONO-S-SA-ALKYL VOLUME TRIETHYLENE GLYCOL

one . .

: The invention relates to a process for the separation of the azeotropic mixture of diethylene glycol (DEG) and mono-C-Cd-alkyl ether of triethylene glycol (TEG). The components of this azeotrope are used in brake and hydraulic fluids, in antifreezes, plasticizers, and as an extractant.

C-C-alkyl esters of TEG are semi-. are usually combined with cellulose or carbitol in the process of obtaining the latter from the corresponding alcohol and ethylene oxide.

When allocating target products (cellulisol, carbitol) | by rectification, the TEG esters are isolated as an azeotropic mixture with side-formed glycols, followed by separation from the latter in a pure one.

The composition of the azeotropic mixture depends on the residual pressure (temperature) of the distillation and contains AO-60 ether.

A known method of separating an azeotropic mixture, for example, of a polyethylene glycol polyethylene glycol alkyl monoether, is that the initial mixture is first treated with a monoaromatic hydrocarbon that is miscible with the latter but immiscible with water at a molar,

to an excess of 0.5-2, and then an aqueous solution of alkali or alkali metal salt p.

The disadvantage of this method is the use of an additional second extractant of an aqueous solution of alkali or alkali metal salt, which complicates the technology (laborious processes take place: filtration

Claims (2)

20 salts, the distillation of products from salt, the formation of precipitation). These drawbacks limit the industrial implementation of the process. 3 The purpose of the invention is to simplify the process. The goal is achieved by the fact that according to the method of separating azeotropic mixture of diethylene glycol and mono-C-Cr-alkyl ether of triethylene glycol by extraction with an aromatic hydrocarbon that is miscible with the separable mixture and not miscible with water, extraction is carried out in the presence of water, in an amount of 8-20 from azeotropic mixture. Use toluene as an aromatic hydrocarbon. The proposed method is carried out in column type extractors in which toluene droplets are bubbled through the bed of substances to be separated. The composition of the extract and raffinate phases is determined by gas-liquid chromatography. Example 1. In a laboratory column extractor, 20 TEG-DEG ethyl ether mixtures were loaded in a ratio of, respectively, 5 F of water was added and mixed. The extraction is carried out in toluene in a continuous manner at 20-30 ° C for 2 hours. Get the ratio of components in the extract phase ether TZGa: DEG 85:15; in the raffinate phase TEG ester: DEG 3,: 9.6. Example 2. Extraction is carried out according to the conditions of example 1, but for 1.5 hours. The ratio of the components is obtained: in the extract phase, the ester of TEG: DEG 90,: 9.6; in the raffinate phase, the air TEGggDEG 15.6: 8 ,. Example Z.K20g of a binary mixture containing tS wt.% Triethylene glycol methyl ether (TEGa) and 52 wt.% Diethylene glycol (DEG), add 1 g water, mix and load into a laboratory column extractor. 50 ml of toluene are poured into the bottom part of the extractor, heated to boiling, ensuring uniform sparging of toluene through the ester-glycol mixture. The extraction process is carried out continuously for 2 hours to establish a practically constant Glycol layer. Extraction and raffinate phases are obtained with a ratio of TEG: DEG methyl ester of 83:17 and 7:93, respectively. Extract and raffinate phases from 8 experiments are collected separately and two distillations are carried out on a laboratory column with an efficiency of 30 theoretical lines. The k fractions are obtained: 1 - toluene and water fraction; 2 - azeotropic fraction from two distillations with a ratio of TEGagDEG methyl ester in: amount of 35 g; 3 - TEG methyl ester containing the main substance weight. in the amount of 56 g. The output for 1 operation is 72, DEG with the content of the main substance 98 in the amount of 59 g. Next, a new series of 8 extraction and 2 runs was performed using a 35 g azeotrope. . The total yield of methyl ester TEGa 88.9, EDGa 89.4. Example k. Negative. To extractor for experiment 1, 20 g of a mixture of the indicated composition is loaded without the addition of water. Observes a mixture of toluene with the initial mixture of TEG-DEG ester, which makes the extraction process impossible. Example 5 - Extraction of TEG ethyl ester under industrial conditions. The industrial plant consists of a 9 m column type extractor, equipped in the lower part with bubblers for feeding toluene, and a distillation unit with a column containing 20 cap plates, and a 12 m cube. Into the extractor, 500 l of water are successively charged, which is to be separated into a mixture of ethyl ester TEG-DEG in a ratio of respectively 290.0 kg and toluene in the amount of bOOO l. I pour 3000 liters of toluene into the cube of the column and turn on the heating, which circulates toluene through the extractor at a speed of 1.3 m / h. The toluene, by bubbling through the ether-glycol layer at 30-40 ° C, extracts the TEG ester and, through the top of the extractor, flows by gravity into the bottom of the column, where it accumulates. The first extraction operation is completed after 8 hours to achieve a constant LEVEL of the interface between two phases in the extractor. Do not drain the diethylene glycol raw from the extractor, reload it again with 500 kg of water and 2900 kg of the mixture of said Soatava, and carry out a second extraction operation. After two operations, distillation of the bottom liquid is carried out. The ether of the TEG collected in the cube of the distillation column is isolated by vacuum distillation. First, an azeotropic fraction in the amount of 1000 kg is selected, whose composition (5B TEG ether and C2% DEGa) is close to the original. 2600 kg of the product were obtained with the content of ethyl ether TEG 97%. Output 72% of theoretical. DEG from the raffinate phase is also purified by vacuum distillation. Azeotropic fraction of the composition of ethyl ester TEG-TEG in the ratio of kQ% S2% respectively in the amount of LZO kg. DAG exit per operation b7%. Get the product with a concentration of the main substance of 98%. Both azeotropic fractions are pooled and subjected to repeated extraction and rectification. 96 Total yield of TZ.Ha 88 ether. Total yield of TEG is 83%. Invention 1. A method for separating a mixture of diethylene glycol and mono-C-Cd-alkyl ether of triethylene glycol by extraction with an aromatic hydrocarbon mixed with a separable mixture and not miscible with water, characterized in that, in order to simplify the process, the extraction is carried out in the presence of water in the amount of 8-20% by weight of the azeotropic mixture. 2. The method according to claim 1, is also distinguished by the fact that toluene is used as an aromatic hydrocarbon. Sources of information taken into account in the examination 1. US Patent No. 269tO 8, cl. 260-615, opubik 195 (prototype).