A catalyst and a method for selectively hydrogenating and removing polychloroacetic acid using the catalyst

Abstract

The invention discloses a catalyst, which is composed of a carrier, a double noble metal loaded on the carrier and a catalyst additive, the carrier is coal-based activated carbon; the double noble metal is Pd and Pt, and the double noble metal accounts for 0.9% of the weight of the catalyst -1.1%; the catalyst promoter is Sn and Mn, and the catalyst promoter accounts for 0.1%-0.5% of the catalyst weight, and simultaneously discloses the method of using the catalyst to carry out selective hydrogenation to remove polychloroacetic acid, specifically Mix monochloroacetic acid solution and hydrogen atmosphere to preheat, then contact with catalyst for hydrodechlorination reaction, the reaction temperature is 150-180°C, the pressure at the top of the reaction tower is 0.07-0.15MPa, and the pressure at the bottom is 0.03-0.09MPa. The catalyst provided by the invention has good stability, and the selectivity of monochloroacetic acid is high when it is used for hydrogenation to remove polychloroacetic acid.

Description

technical field [0001] The invention belongs to the technical field of catalytic hydrodechlorination, and in particular relates to a catalyst and a method for selectively hydrogenating and removing polychloroacetic acid using the catalyst. Background technique [0002] Chloroacetic acid is an important chemical intermediate, mainly used in dyes, pesticides, medicines and synthetic resins. With the increase in demand for downstream products, the demand for chloroacetic acid is also increasing year by year. The traditional acetic acid production method is the sulfur method. Although the investment is small, the production efficiency is low, the product purity is not competitive, and the process has serious environmental protection problems. Therefore, it is gradually being replaced by the continuous hydrogenation method of acetic anhydride, which has a large production capacity , High product purity, high automation purity, by-products can be converted into hydrochloric acid, ...

AI Technical Summary

Problems solved by technology

The dechlorination reaction is relatively sensitive to pressure, and the increase in pressure will increase the activity of the catalyst, resulting in too fast a catalytic reaction rate, which may dechlorinate part of monochloroacetic acid into acetic acid

In the prior art, the reaction pressure of catalytic hydrogenation to remove polychloroacetic acid is basically greater than 0.2MPa, between 0.2-1.0MPa. Only under the condition of this pressure range can the normal flow of materials and the normal progress of the reaction be guaranteed; If the reaction pressure is directly reduced, the material flow will be too slow, and the contact time with the catalyst will be too long, resulting in excessive dechlorination reaction, resulting in a decrease in the selectivity of the product

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