Supported catalyst for preparing 2,5-dichlorophenol through catalytic oxidation, and application thereof

Abstract

The invention discloses a vanadium oxide/TS-1 heterogeneous catalyst obtained by combining vanadyl acetylacetonate and a TS-1 type titanium-silicon molecular sieve. The preparation method comprises the following steps: dissolving vanadyl acetylacetonate in methanol, adding a TS-1 type titanium-silicon molecular sieve, and carrying out stirring, dipping, filtering, freeze-drying, roasting and othersteps to obtain the VOX/TS-1 supported catalyst with the vanadium content of 1-5%. According to the invention, the preparation method is simple, the cost is low, and the yield is 100% in terms of vanadium; and by using the vanadium oxide/TS-1 as a catalyst, the catalytic efficiency can be improved while the excessive oxidation of 2,5-dichlorophenol can be effectively inhibited, the excessive oxidation product can be controlled to be 5% or less, the selectivity of 2,5-dichlorophenol can achieve 95% or more, especially the isomer 2,4-dichlorophenol can be significantly inhibited, the selectivity of 2,4-dichlorophenol is less than 0.1%, and the supported catalyst has advantages of easy recovery and reutilization.

Description

technical field [0001] The invention belongs to the technical field of 2,5-dichlorophenol preparation, and in particular relates to a supported catalyst and its application in the preparation of 2,5-dichlorophenol by catalytic oxidation of 1,4-dichlorobenzene. Background technique [0002] 2,5-Dichlorophenol is mainly used as intermediates of medicines and dyes, herbicide dicamba intermediates, nitrogen fertilizer synergists, leather antifungal agents, etc., especially the main organic intermediates for the preparation of pesticide herbicide dicamba. In recent years, with the continuous improvement of greenhouse gas emission reduction and environmental protection requirements, and the banning and restricted use of chlorsulfuron-methyl and metsulfuron-methyl preparations, the demand for dicamba, a low-toxicity pesticide widely used in crop production, continues to increase, and the market prospect is good . Therefore, the research and development of 2,5-dichlorophenol interm...

AI Technical Summary

Problems solved by technology

This process has the advantages of simple process route and low investment, but this method needs to use a large amount of acid and alkali, and the reaction conditions are relatively harsh. During the production process, a large amount of acid-base waste liquid and solid salt are produced, and there is a serious environmental pollution problem. And the separation of by-products is difficult

[0005] 2. The patent US 4326882 discloses that 2,5-dichloroaniline is used as raw material to prepare 2,5-dichlorophenol through diazotization and hydrolysis; this method is technically mature and widely used in industry, but it needs A large amount of organic and inorganic reagents are used, and the amount of waste water is large. For every ton of 2,5-dichlorophenol produced, about 10 tons of phenolic waste water will be produced.

However, the catalytic effect is not ideal and the product selectivity is low

Such as Chinese patent CN107129426A discloses a kind of preparation method of 2,5-dichlorophenol, under the effect of oxidizing agent, metal porphyrin catalyst and cocatalyst, take 1,4-dichlorobenzene as raw material, water, methanol, acetonitrile, One or more than one composition in acetic acid is used as a solvent and prepared by catalytic oxidation; this method is to improve the efficiency and yield of the oxidation reaction through a catalytic system composed of a metalloporphyrin catalyst and a cocatalyst. It can be seen that it can be used alone Metalloporphyrin catalyst, catalytic effect is still unsatisfactory

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