Method for purification of monochloroacetic acid by catalytic distillation

A technology of catalytic rectification and monochloroacetic acid, which is applied in chemical instruments and methods, separation/purification of carboxylic acid compounds, preparation of organic compounds, etc., can solve the problem of reducing the purity of monochloroacetic acid, difficult rectification and separation, sulfur method Low efficiency and other problems, to achieve the effect of easy scale-up production and application, good mass and heat transfer effect, and high selectivity

Active Publication Date: 2018-11-30
XIAN CATALYST NEW MATERIALS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The production of monochloroacetic acid needs acetic acid and chlorine gas. The current mainstream production methods are sulfur method and acetic anhydride method. The sulfur method is inefficient and has serious environmental protection problems. higher cost
These two production methods will produce dichloroacetic acid or trichloroacetic acid, which reduces the purity of monochloroacetic acid. Since the boiling points of monochloroacetic acid, dichloroacetic acid and trichloroacetic acid are relatively close, conventional rectification and separation are more difficult and costly. high

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] 1. Catalyst loading

[0022] The catalyst diluted with coal-based activated carbon is filled in the fixed-bed catalytic distillation tower. According to the dilution ratio of the catalyst, there are stripping section, catalytic section and rectifying section from bottom to top, and the catalyst in the stripping section, catalytic section and rectifying section. The mass fraction of is 10%, 80% and 10% successively, wherein the loading amount of Pt in the catalyst is 0.2%, the loading amount of Pd is 0.8%, the loading amount of Ag is 0.1%, and the loading amount of Mg is 0.2% , The loading of Al is 0.3%, and the rest is coal-based activated carbon.

[0023] 2. Pretreatment

[0024] Pass through the bottom of the fixed-bed catalytic distillation tower with nitrogen to replace the air in the tower for 2 hours, then switch the nitrogen to pure hydrogen, and at the same time raise the temperature to 200°C at a rate of 1°C / min and keep it for 3 hours to activate and pretreat...

Embodiment 2

[0028] 1. Catalyst loading

[0029] The catalyst diluted with coal-based activated carbon is filled in the fixed-bed catalytic distillation tower. According to the dilution ratio of the catalyst, there are stripping section, catalytic section and rectifying section from bottom to top, and the catalyst in the stripping section, catalytic section and rectifying section. The mass fraction of is 10%, 80% and 10% successively, wherein the loading amount of Pt in the catalyst is 0.5%, the loading amount of Pd is 0.5%, the loading amount of Ag is 0.1%, and the loading amount of Mg is 0.2% , The loading of Al is 0.2%, and the rest is coal-based activated carbon.

[0030] 2. Pretreatment

[0031] Pass through the bottom of the fixed-bed catalytic distillation tower with nitrogen to replace the air in the tower for 2 hours, then switch the nitrogen to pure hydrogen, and at the same time raise the temperature to 200°C at a rate of 1°C / min and keep it for 3 hours to activate and pretreat...

Embodiment 3

[0035] 1. Catalyst loading

[0036]The catalyst diluted with coal-based activated carbon is filled in the fixed-bed catalytic distillation tower. According to the dilution ratio of the catalyst, there are stripping section, catalytic section and rectifying section from bottom to top, and the catalyst in the stripping section, catalytic section and rectifying section. The mass fraction of is 10%, 70% and 20% successively, wherein the loading amount of Pt in the catalyst is 0.4%, the loading amount of Pd is 0.5%, the loading amount of Ag is 0.1%, and the loading amount of Mg is 0.2% , The loading of Al is 0.1%, and the rest is coal-based activated carbon.

[0037] 2. Pretreatment

[0038] Pass through the bottom of the fixed-bed catalytic distillation tower with nitrogen to replace the air in the tower for 2 hours, then switch the nitrogen to pure hydrogen, and at the same time raise the temperature to 200°C at a rate of 1°C / min and keep it for 3 hours to activate and pretreat ...

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Abstract

The invention discloses a method for purification of monochloroacetic acid by catalytic distillation. According to the method, trichloroacetic acid and dichloroacetic acid in a trichloroacetic acid, dichloroacetic acid, monochloroacetic acid and acetic acid mixture are converted into monochloroacetic acid by a fixed bed catalytic distillation column, the selectivity is over 98%, and the rest is the acetic acid. A catalyst is a noble metal catalyst supported on coal-based activated carbon. After preheating, the mixture and hydrogen enter the fixed bed catalytic distillation column from the middle and the bottom of the column respectively. Controllable dechlorination reaction takes place on the surface of the catalyst. Hydrogen chloride, by-product acetic acid and residual hydrogen are discharged from the top of the column, high-purity acetic acid can be obtained, and the monochloroacetic acid with higher boiling point is obtained from the bottom of the column. The purity of the monochloroacetic acid is over 99%.

Description

technical field [0001] The invention belongs to the technical field of selective catalytic hydrogenation, in particular to a method for preparing high-purity monochloroacetic acid through selective catalytic hydrogenation and dechlorination. Background technique [0002] Monochloroacetic acid is an important chemical intermediate, mainly used in agriculture, medicine, fuel and other industries, and is an important raw material for the production of pesticides, herbicides, chloroacetates and active fuels. The production of monochloroacetic acid needs acetic acid and chlorine gas. The current mainstream production methods are sulfur method and acetic anhydride method. The sulfur method is inefficient and has serious environmental protection problems. higher cost. These two production methods will produce dichloroacetic acid or trichloroacetic acid, which reduces the purity of monochloroacetic acid. Since the boiling points of monochloroacetic acid, dichloroacetic acid and tri...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C53/16C07C51/377C07C51/44
CPCC07C51/377C07C51/44C07C53/16Y02P20/10
Inventor 林涛程杰万克柔张炳亮张力陈丹张之翔曾永康曾利辉高武
Owner XIAN CATALYST NEW MATERIALS CO LTD
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