Production method and production system for 2,4-dichlorophenol

Abstract

The invention provides a production system for 2,4-dichlorophenol. The production system comprises a fixed-bed reactor, which comprises a phenol feeding port, a sulfuryl chloride feeding port and a discharge outlet, and is provided with a supported metal salt catalyst; a deacidification tower, which comprises a feed inlet, a gas discharge outlet and a liquid discharge outlet, wherein the feed inlet of the deacidification tower communicates with the discharge outlet of the fixed-bed reactor; and a rectifying tower, wherein the feed inlet of the rectifying tower communicates with the liquid discharge outlet of the deacidification tower. Compared with the prior art, the production system provided by the invention has the following advantages: the supported metal salt catalyst is fixed in thefixed-bed reactor for continuous usage and is not in a same system with phenol and a metal catalyst, so impurities in a reaction solution used in a chlorination reaction are reduced, the reaction solution can be easily separated and purified, a finally rectified substance has no solid residue, and a reaction route is clean and environment-friendly.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, in particular to a production method and production system of 2,4-dichlorophenol. Background technique [0002] 2,4-Dichlorophenol is used as a solvent, pesticide and pharmaceutical intermediate for the synthesis of biben, 2,4-D, ibifos (EPBP), dukesan, glyphosate and the drug thiobisdichlorophene, The annual demand is tens of thousands of tons. [0003] The production methods of 2,4-dichlorophenol mainly include: phenol direct chlorination method, mixed phenol chlorination method, o-chlorophenol selective chlorination method, p-chlorophenol chlorination method and phenol catalytic chlorination method. [0004] The direct chlorination of phenol is a traditional production process at home and abroad. The process is simple and the cost is low. However, because the physical properties of the by-product 2,6-dichlorophenol are very close to those of 2,4-dichlorophenol, it is difficult to se...

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Problems solved by technology

[0010] The Chinese patent with the publication number CN105777499A discloses a method for directional synthesis of 2,4-dichlorophenol and 2,4,6-trichlorophenol with sulfuryl chloride plus a composite catalyst. It is mentioned that 98% of 2, 4-dichlorophenol, but due to the use of expensive sulfuryl chloride, and the subsequent use of molten crystallization for separation, it will inevitably lead to the mixing of low-melting catalysts and oxidative and discolored substances during chlorination into the target product, resulting in poor appearance of the product and containing Certain impurities will affect subsequent use and make it difficult to implement industrialization

[0011] In addition, most of the existing chlorination adopts intermittent kettle-type chlorination. Sampling and analysis are required during the chlorination process. At the same time, sulfuryl chloride is dripped intermittently, resulting in unstable gas output, which in turn makes it difficult to control the reuse of sulfur dioxide. At the same time, the metal Salt catalyst recovery is difficult and environmental protection costs are high

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