Catalyst for preparing 2,3-dichloropyridine and preparation method and application of catalyst

Abstract

The invention discloses a catalyst for preparing 2,3-dichloropyridine and a preparation method and application of the catalyst. The catalyst is prepared from an activated carbon carrier, metal Pd, noble metal S1 and transition metal S2, wherein the weight percentage of Pd is 1-4%, the weight percentage of S1 is 0-3%, the weight percentage of S2 is 0-2%, the balance is the activated carbon carrier;the sum of the weights of Pd, S1 and S2 accounts for 2-6% of the total weight of the catalyst; the content of S1 and the content of S2 could not be 0 at the same time; S1 is one of spongy Ir, Au or Pt; and S2 is one of Mn, Co or Zn. The catalyst provided by the invention has dechlorination activity to a certain extent, but can avoid an excessive dechlorination side effect. When the catalyst is used for preparing the 2,3-dichloropyridine, the conversion rate is 100%, and the selectivity of the 2,3-dichloropyridine is greater than 95%; corrosion to a reaction still and subsequent pipelines canbe avoided.

Description

technical field [0001] The invention belongs to the technical field of catalysts, and in particular relates to a catalyst for preparing 2,3-dichloropyridine and a preparation method and application thereof. Background technique [0002] 2,3-Dichloropyridine is an important pesticide intermediate compound, which is mainly used for the synthesis of chlorantraniliprole. With the large-scale application and promotion of the new pesticide chlorantraniliprole, 2,3-dichloropyridine The market demand is rapidly increasing. Using 3-aminopyridine as raw material, 2,3-dichloropyridine can be synthesized through the steps of chlorination, diazotization, hydrolysis, etc., but this method has many three wastes, which can no longer meet the current environmental protection requirements for chemical industry, so actively explore new methods. Synthetic methods and routes are of great significance. In recent years, the route of producing 2,3-dichloropyridine using 2,6-dichloropyridine as ra...

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Problems solved by technology

[0003] Chinese patent CN107721913A discloses a preparation method of 2,3-dichloropyridine, which adopts the method of chlorination and dechlorination of 2,6-dichloropyridine, but the selectivity of the dechlorination reaction is not high, and the raw materials cannot be completely converted , subsequent rectification is required to separate raw materials and products, and the cost is relatively high

Chinese patent CN107056688A discloses a kind of preparation method of 2,3-dichloropyridine, this method adopts palladium nickel silica catalyst, and the temperature and pressure of reaction are higher, probably because this catalyst activity is not as high as palladium charcoal activity high, conversion rate reaches 93.4%, selectivity 89.2%, this method also has the problem that the raw material cannot be completely converted, and the selectivity is not high, and the high activity of the nickel catalyst may cause excessive dechlorination side reactions

[0004] In the Chinese patent CN105642280A, a method for continuous production of 2,3-dichloropyridine is disclosed. The fixed bed continuous process technology is adopted, and the catalytic reaction efficiency is high, but the conversion rate and selectivity are still not ideal, and there are more or less dechlorination phenomena. , long-term operation is easy to corrode the equipment, because the one-time investment cost of the fixed bed equipment is relatively large, if there is corrosion of the equipment caused by dechlorination, it will also increase the operating cost, so it is necessary to continue to improve and optimize before the industrial application

Moreover, the hydrogen chloride generated by dechlorination in the fixed-bed continuous process needs to go through the entire reaction system, and can only be discharged after gas-liquid separation, so it may cause corrosion of equipment where materials such as reactors, pipelines, and gas-liquid separation pass. Even enamelled equipment commonly used in industry is prone to corrosion, so it needs to be inspected and replaced regularly

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