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Separation process of removing dimethyl ether impurities in chloromethane through water absorption

A technology of dimethyl ether and methyl chloride, applied in the field of gas separation and purification, can solve problems such as low solubility of methyl chloride, and achieve the effects of simple regeneration process and low regeneration energy consumption

Inactive Publication Date: 2015-09-23
DALIAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Obviously different from dimethyl ether, it is difficult for methyl chloride to undergo hydrogen bonding with water, so the solubility of methyl chloride in water is very small

Method used

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  • Separation process of removing dimethyl ether impurities in chloromethane through water absorption
  • Separation process of removing dimethyl ether impurities in chloromethane through water absorption
  • Separation process of removing dimethyl ether impurities in chloromethane through water absorption

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Crude methyl chloride (S-1) from the dehydration unit with a flow rate of 450Nm 3 / h, containing 75mol% of methyl chloride and 25mol% of dimethyl ether, enters the absorption tower (1) from the bottom under the conditions of 0.2MPaG and 15°C, and flows from bottom to top.

[0027] The fresh absorbent (S-2, pure water, the supplementary amount is about 6kg / h) and the cooled regenerated absorbent (S-8) are joint stock, with a total flow rate of 3.75t / h, and enter the absorption tower (1) from the top , flowing from top to bottom.

[0028] In the absorption tower (1), the dimethyl ether impurity enters the liquid phase by the gas phase due to the hydrogen bond, and most of the methyl chloride cannot enter the absorbent; the absorption tower (1) top extracts the methyl chloride ( S-3), the volume flow rate is 335Nm 3 / h, the dimethyl ether content is then reduced to 0.3mol%; the rich absorption liquid (S-4) is extracted from the bottom of the absorption tower (1), the con...

Embodiment 2

[0037] Crude methyl chloride (S-1) from the dehydration unit with a flow rate of 450Nm 3 / h, containing 75mol% of methyl chloride and 25mol% of dimethyl ether, enters the absorption tower (1) from the bottom under the conditions of 0.5MPaG and 35°C, and flows from bottom to top.

[0038] The fresh absorbent (S-2, pure water, the supplementary amount is about 6kg / h) and the cooled regenerated absorbent (S-8) are joint stock, with a total flow rate of 2.98t / h, and enter the absorption tower (1) from the top , flowing from top to bottom.

[0039] In the absorption tower (1), the dimethyl ether impurity enters the liquid phase by the gas phase due to the hydrogen bond, and most of the methyl chloride cannot enter the absorbent; the absorption tower (1) top extracts the methyl chloride ( S-3), the volume flow rate is 328Nm 3 / h, the dimethyl ether content is then reduced to 0.3mol%; the rich absorption liquid (S-4) is extracted from the bottom of the absorption tower (1), the con...

Embodiment 3

[0048] Crude methyl chloride (S-1) from the dehydration unit with a flow rate of 450Nm 3 / h, containing 75mol% of methyl chloride and 25mol% of dimethyl ether, enters the absorption tower (1) from the bottom under the conditions of 0.2MPaG and 15°C, and flows from bottom to top.

[0049] Fresh absorbent (S-2, CaCl 2 The aqueous solution with a mass concentration of 15%, the supplementary amount is about 2kg / h) is combined with the cooled regenerated absorbent (S-8), and the total flow rate is 4.5t / h, and enters the absorption tower (1) from the top. flow down.

[0050] In the absorption tower (1), the dimethyl ether impurity enters the liquid phase by the gas phase due to the hydrogen bond, and most of the methyl chloride cannot enter the absorbent; the absorption tower (1) top extracts the methyl chloride ( S-3), the volume flow rate is 336Nm 3 / h, the dimethyl ether content is then reduced to 0.2mol%; the rich absorption liquid (S-4) is extracted from the bottom of the ab...

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Abstract

The invention provides a separation method and process of removing dimethyl ether impurities in chloromethane by using water as an absorbent, and belongs to the field of gas separation and purification. Based on the chemical theory that hydrogen bonds are formed by polar gas molecules and water, a significant difference of water solubility properties between chloromethane and dimethyl ether is used, water is used as an absorbent or a mixture of water and another material is used as an absorbent to replace traditional concentrated sulfuric acid, and a joint process formed by combining absorption and rectification is used, so as to separate a mixture of chloromethane and dimethyl ether safely and efficiently in low cost. By using the separation method and process, in which water is used as the absorbent, to treat a passivated tail gas produced by a dehydration apparatus, the removal rate of dimethyl ether is greater than 99%, the concentration of purified chloromethane can reach 99 mol%, and the recovery rate of the chloromethane can be kept at about 98%. Furthermore, because a chemical reaction is avoided, separated dimethyl ether from which chloromethane is removed through hydrolysis can be used as a byproduct, thus increasing the economic benefit.

Description

technical field [0001] The invention relates to a separation method and process for removing dimethyl ether impurities in methyl chloride by using water (which may be pure water or a mixture of water and other substances) as an absorbent, and belongs to the field of gas separation and purification. Based on the chemical theory that polar gas molecules form hydrogen bonds with hydrogen ions in water, the method takes advantage of the significant difference in the solubility properties of methyl chloride and dimethyl ether in water, and uses water as the absorbent instead of traditional concentrated sulfuric acid, which is safe, efficient and low-cost. A mixture of methyl chloride and dimethyl ether is separated cost-effectively. Background technique [0002] Chloromethane (CH 3 Cl) is very important in the organic synthesis industry, and is widely used as a solvent, refrigerant, and methylating reagent. With the rapid development of organosilicon and special rubber synthesi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C17/38C07C19/03C07C41/34C07C43/04
Inventor 阮雪华杨招艺贺高红代岩焉晓明郑文姬张宁
Owner DALIAN UNIV OF TECH
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