Liquid-liquid extraction-azeotropic rectification mixing process for separating propylene glycol monomethyl ether and water

A technology of propylene glycol methyl ether and azeotropic distillation, which is applied in ether separation/purification, ether preparation, organic chemistry, etc. It can solve the problems of complex operation, separation and purification without other mixtures, and inability to achieve efficient separation, so as to solve the problem of separation difficult effect

Inactive Publication Date: 2019-01-22
QINGDAO UNIV OF SCI & TECH
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Problems solved by technology

The separation process is the most energy-consuming link in industrial production. Propylene glycol methyl ether and water can form the lowest azeotrope, and ordinary distillation operations cannot achieve efficient separation. Therefore, it is of great significance to seek a low-energy, high-efficiency separation method. Economic value and environmental benefits
[0003] There are binary azeotropes in the mixture of propylene glycol methyl ether and water, which cannot be effectively separated by ordinary rectification
[0004] Chinese patent CN107032966A discloses a recovery process of propylene glycol methyl ether. This process uses 2-ethylhexanoic acid as an extraction agent, and a large amount of water is removed with a liquid-liquid extraction tower and then separated by a rectification tower to obtain the finished product propylene glycol methyl ether. There is a problem with high energy consumption
However, the process is complicated to operate and only high-purity methanol can be obtained, and other mixtures are not separated and purified.

Method used

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  • Liquid-liquid extraction-azeotropic rectification mixing process for separating propylene glycol monomethyl ether and water

Examples

Experimental program
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Effect test

Embodiment 1

[0032] The feed temperature is 45° C., the flow rate is 1000 kmol / h, and the pressure is 1 atm absolute pressure. The feed contains 92.2 mol% of propylene glycol methyl ether and 7.8 mol% of water. The theoretical plate number of the liquid-liquid extraction tower is 15, the feeding position of the propylene glycol methyl ether-water mixture is the 15th block, the feeding position of the extractant is the 1st block, the theoretical plate number of the azeotropic distillation column is 22, and the feeding position is Be the 11th piece, the theoretical plate number of recovery tower is 13 pieces, the 8th piece of feeding position, the flow rate of extraction agent is 250kmol / h (solvent ratio is 0.25), the volume of 2-ethylhexanoic acid and chloroform in the mixed extraction agent The molar mass ratio of the propylene glycol methyl ether after separation is 0.4, and the purity of the separated propylene glycol methyl ether is 99.90% (mol fraction), and the purity of water is 99.92...

Embodiment 2

[0034] The feed temperature is 45° C., the flow rate is 1000 kmol / h, and the pressure is 1 atm absolute pressure. The feed contains 92.2 mol% of propylene glycol methyl ether and 7.8 mol% of water. The number of theoretical plates of the liquid-liquid extraction tower is 13, the feeding position of the propylene glycol methyl ether-water mixture is the 13th, the feeding position of the extractant is the 1st block, the number of theoretical plates of the azeotropic distillation column is 20, and the feeding position is the 1st 9 blocks, the theoretical plate number of the recovery tower is 11 blocks, the 7th block of the feed position, the flow rate of the extractant is 400kmol / h (solvent ratio is 0.4), the mole of 2-ethylhexanoic acid and chloroform in the mixed extractant The mass ratio is 0.5, the purity of the separated propylene glycol methyl ether is 99.92% (mol fraction), and the purity of water is 99.91% (mol fraction).

Embodiment 3

[0036] The feed temperature is 45° C., the flow rate is 1000 kmol / h, and the pressure is 1 atm absolute pressure. The feed contains 92.2 mol% of propylene glycol methyl ether and 7.8 mol% of water. The number of theoretical plates of the liquid-liquid extraction tower is 11, the feed position of the propylene glycol methyl ether-water mixture is the 11th block, the feed position of the extractant is the 1st block, the number of theoretical plates of the azeotropic distillation column is 18, and the feed position is Be the 10th piece, the theoretical plate number of recovery tower is 10 pieces, the 6th piece of feed position, the flow rate of extraction agent is 500kmol / h (solvent ratio is 0.5), the 2-ethylhexanoic acid and chloroform in the mixed extraction agent The molar mass ratio of the propylene glycol methyl ether after separation is 0.55, and the purity of the separated propylene glycol methyl ether is 99.99% (mol fraction), and the purity of water is 99.94% (mol fractio...

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Abstract

The invention relates to a liquid-liquid extraction-azeotropic rectification mixing process for separating propylene glycol monomethyl ether and water. Firstly, a mixed extracting agent IS prepared byusing extracting agents 2-ethylhexoic acid and chloroform according to a certain ratio liquid-liquid extraction is performed on a propylene glycol methyl ether water solution, wherein the purity of the water in a raffinate phase at the top of a liquid-liquid extraction tower can reach more than 99.9 mol %, and an extraction phase is conveyed to an azeotropic rectification tower for azeotropic rectification. A phase separator is added to the upper part of the azeotropic rectification tower, water is collected from the upper part of the phase separator, chloroform is collected from the lower part of the phase separator for recycling the extracting agent, and a 2-ethylhexoic acid and propylene glycol monomethyl ether mixed solution at the bottom of the azeotropic rectification tower is conveyed to a recovery tower for separation. The product propylene glycol monomethyl ether is extracted from the top of the recovery tower, and the purity of the propylene glycol monomethyl ether is more than 99.9 mol %, and the extraction agent 2-ethylhexoic acid at the bottom of the tower is recycled. Devices mainly comprise the liquid-liquid extraction tower (LEC), the extraction rectifying tower (T1), the recovery tower (T2), a condenser (C1), a condenser (C2), a condenser (C3), a reflux tank (D1), a reboiler (R1), a reboiler (R2), a mixer (Mix), a flow divider (Fs) and a phase separator (DEC).

Description

【Technical field】 [0001] The invention belongs to the field of separation and purification in the chemical industry, and in particular relates to a liquid-liquid extraction-azeotropic rectification mixing process for separating propylene glycol methyl ether and water. 【Background technique】 [0002] Propylene glycol methyl ether (PM) is an important "universal solvent", dispersant, thinner, and can also undergo esterification with acetic acid to form one of the most commonly used esters with high industrial demand in surface coatings. Propylene glycol methyl ether Acetate, water are by-products of this reaction. Therefore, dehydration of propylene glycol methyl ether is an important and necessary operation. The separation process is the most energy-consuming link in industrial production. Propylene glycol methyl ether and water can form the lowest azeotrope, and ordinary distillation operations cannot achieve efficient separation. Therefore, it is of great significance to s...

Claims

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Application Information

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IPC IPC(8): C07C41/42C07C41/38C07C43/13
CPCC07C41/38C07C41/42C07C43/13
Inventor 王英龙戴姚于萌潇朱兆友崔培哲
Owner QINGDAO UNIV OF SCI & TECH
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