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Separation method of difluoroethanol-water azeotrope

A difluoroethanol, water azeotrope technology, applied in the chemical industry, can solve the problems of large pollution, impact on human health, only purity, etc., and achieve the effect of small pollution

Inactive Publication Date: 2017-06-09
XIAN MODERN CHEM RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But realize in the enforcement process of above-mentioned invention, there are following problems: (1) adding of entrainer makes product contain entrainer, influences the application of difluoroethanol in medicine and cleaning agent; (2) azeotropic rectification difluoroethanol The purity of the ethanol product is only 98.8%, and the purity is relatively low; (3) the entrainer is highly toxic, affects human health, and is flammable and explosive, which pose a threat to the safety and health of operators; (4) the azeotropic distillation process The toluene content in the wastewater produced in the
The existence of the above problems has seriously hindered the industrialization of difluoroethanol

Method used

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  • Separation method of difluoroethanol-water azeotrope

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] A mixture of 80% by mass of difluoroethanol and 20% by mass of water is fed from the middle of rectification tower A at a temperature of 80°C, and gas-liquid is carried out in rectification tower A under a pressure of 100kPa. Phase separation, reflux ratio 2, tower top temperature 92°C, azeotrope of difluoroethanol and water at the top of tower A; temperature of distillation tower A bottom is 95°C, tower bottom is difluoroethanol, purity 99.95%.

[0029] The temperature of the azeotrope of difluoroethanol and water drops to 60°C and enters the pervaporation device B. The feed liquid side is operated at a pressure of 100kPa. To rectification column A, the permeate is water with an organic content of 0.001%.

Embodiment 2

[0031] The mass percentage content of difluoroethanol is 75% and the mixture of water mass percentage content is 25%. The phases are separated, the reflux ratio is 3, the top temperature is 98°C, and the top of tower A is an azeotrope with water; the temperature of the distillation column A bottom is 101°C, and the bottom bottom is difluoroethanol with a purity of 99.92%.

[0032] The temperature of the azeotrope of difluoroethanol and water drops to 60°C and enters the pervaporation device B. The feed liquid side is operated at a pressure of 120kPa, the feed liquid measurement operating temperature is 60°C, and the pressure behind the membrane is 1kPa. In rectification column A, the permeate is water, and the organic matter content is 0.0015%.

Embodiment 3

[0034] Difluoroethanol mass percentage content is 80% and the mixture of water mass percentage content is 20% under the condition of temperature 95 ℃, feeds from the middle part of rectifying tower A, under the pressure of 200kPa, gas-liquid is carried out in rectifying tower A The phases are separated, the reflux ratio is 5, the top of tower A is an azeotrope of difluoroethanol and water, and the temperature at the top of the tower is 113°C; the temperature of the bottom of rectification tower A is 116°C, and the bottom of the tower is difluoroethanol, with a purity of 99.93%.

[0035] The temperature of the azeotrope of difluoroethanol and water drops to 60°C and enters the pervaporation device B. The feed liquid side is operated at a pressure of 200kPa. In rectification column A, the permeate is water, and the organic matter content is 0.0012%.

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Abstract

The invention discloses a separation method of a difluoroethanol-water azeotrope, and mainly solves the problems of introduction of a third impurity and low separation purity in the azeotropic distillation. The method adopts a rectification tower and a pervaporation device, and comprises the following steps: (1) a difluoroethanol-water mixture enters a rectification tower to be separated, wherein the overhead fraction is a difluoroethanol-water lowest azeotrope, and the tower bottom fraction is the difluoroethanol product; and (2) the tower bottom fraction of the rectification tower enters the pervaporation device to be separated, water at the liquid side previously penetrates through the membrane to enter the membrane, and the retentate is circulated to the rectification tower after being condensed, wherein the infiltrate is pure water. The method does not introduce the third substance, and has the advantage of high product purity.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and in particular relates to a separation method of difluoroethanol and water azeotrope. Background technique [0002] Difluoroethanol is a basic fluorine-containing organic intermediate with high added value and good development prospects. It is widely used in the fields of medicine, pesticides, cleaning agents and fluoropolymers. In the production process of difluoroethanol produced by transesterification of difluoroethyl acetate and methanol or hydrolysis of 1-chloro-2,2-difluoroethane, water is formed in the product. Since the boiling points of water (boiling point: 100°C) and difluoroethanol (boiling point: 95°C) are very close, the two form the lowest azeotrope, and it is difficult to separate them by conventional distillation. [0003] In industry, azeotropic distillation is generally used to separate the lowest azeotrope, such as the aqueous solution of p-difluoroethanol in CN ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C31/38C07C29/76
CPCC07C29/76C07C31/38
Inventor 袁俊杨建明吕剑惠丰李亚妮张前李江伟赵锋伟余秦伟王为强梅苏宁
Owner XIAN MODERN CHEM RES INST
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