Method for manufacturing monochloroacetic acid based on continuous catalytic chlorination process

Abstract

This invention relates to a method for producing chloroacetic acid by the reaction of glacial acetic acid with the chlorine gas under the effect of the compound catalyst, followed by continuous feeding, continuous distillation and continuous chlorination catalytic reaction. Wherein: load weighted acetic acid in the chlorination reactor, and use it as standard substance, cool the cryostat to the set temperature and turn on the pump for circulation, the temperature controller controls the reactor heating temperature between 100 and 105Deg C, sequentially add 3-8% major catalyst ethyl anhydride, assistant catalyst concentrated sulfuric acid 0.8%, start the venting of the chlorine gas and start timing; then cool down the temperature using condenser low-temperature bath, the residue gas is absorbed by water and concentrated alkaline solution respectively and then discharged, timinly sample for analysis, so as to produce the chloroacetic acid with more than 99% content. This invention is characterized of mild reaction condition, high catalyst activity, specific catalyst effect, high product selectivity, 'clean' process, easy separation and environmental friendly.

Description

technical field [0001] The invention relates to a reactive distillation method, in particular to a method for preparing monochloroacetic acid based on a continuous catalytic chlorination method through continuous feeding and continuous rectification by introducing chlorine gas into glacial acetic acid under the action of a composite catalyst for reaction. Background technique [0002] At present, there are more than ten kinds of synthesis methods of chloroacetic acid, such as acetic acid chlorination method, trichlorethylene hydration method, chloroethanol oxidation method, tetrachloroethane hydrolysis method, glycolic acid chlorination method, acetic anhydride chlorination method, sulfur Acyl chloride chlorination, 1,2-dichloroethane photocatalytic oxidation, polychloroacetic acid reduction and chloroacetyl chloride hydrolysis, etc. However, most of these methods are still in the pilot stage, and only acetic acid chlorination, trichlorethylene hydration, and chloroacetyl ch...

AI Technical Summary

Problems solved by technology

[0003] Among the methods used in industrial production to prepare monochloroacetic acid, the most widely used method is the chlorination of glacial acetic acid. This method is to use glacial acetic acid to react with chlorine gas under the catalysis of sulfur (or red phosphorus), and then crystallize and separate And make, the problem that this technique exists is, yield is low, and raw material consumption is high

[0004] The chloroacetic acid production technique disclosed in CN1382680A is a kind of technique improved for improving product yield, and its technical scheme is to add chlorine inhibitor before the chlorination reaction stage, and chlorine inhibitor can adopt manganese acetate, manganous chloride, chlorine With zinc chloride, zinc acetate or chromium acetate, the final product yield can be increased by 2 to 3% by adding chlorine inhibitors, but these processes generally have the problem that the mother liquor cannot be recycled

[0005] JP-A-7326738 discloses a method for the production of monochloroacetic acid, which includes the use of hydrogen peroxide to oxidize chloroacetaldehyde at a temperature almost equal to the reflux temperature of the reaction mixture, and there are many by-products, which are difficult to separate

[0006] The CN1063677A patent mentions that sulfur is used as a catalyst. Although the process is low in cost, the yield is low. Sulfur powder itself is solid, which can easily cause equipment blockage, which is not good for operation and equipment maintenance, and is also easy to pollute chloroacetic acid products and by-products Hydrochloric acid, which reduces the grade of the product and limits the scope of application of the product

Although the product purity of this process is high, the preparation process is quite complicated, the process is long, and there are many operating steps, which is not conducive to the operation of large devices.

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