System and process for continuously preparing 4-methyl-5-chlorobenzenesulfonic acid

Abstract

The invention discloses a system and a process for continuously preparing 4-methyl-5-chlorobenzenesulfonic acid, the system comprises a jet loop reactor, a circulating pump, a feed pump, a heat exchanger, a gas-liquid separator, a spray absorption tower, a liquid delivery pump and a crude product tank, a discharge port at the lower end of the jet loop reactor is sequentially connected with the circulating pump and the heat exchanger; an outlet of the heat exchanger is connected with a feed port of the jet loop reactor to form a circulation loop, a discharge port at the upper end of the jet loop reactor is connected with the gas-liquid separator through a pipeline, a discharge port at the lower end of the gas-liquid separator is connected with the crude product tank through a pipeline, and a side discharge port of the gas-liquid separator is connected with the spray absorption tower; the liquid delivery pump is connected with the spray absorption tower to form a circulating spray loop, and the barrel of the jet loop reactor is divided into an upper loop reaction section and a lower complete mixing reaction section through a partition plate. By optimizing the structural design of the jet loop reactor, the effects of fully mixing gas and liquid and controlling the chlorination depth are achieved, the product yield is high, and the selectivity is good.

Description

technical field [0001] The invention belongs to the technical field of preparation of 4-methyl-5-chlorobenzenesulfonic acid, and in particular relates to a system and a process for continuously preparing 4-methyl-5-chlorobenzenesulfonic acid. Background technique [0002] 4-Methyl-5-chlorobenzenesulfonic acid is an intermediate product of acid synthesis, and it is usually prepared industrially with p-toluenesulfonic acid and chlorine as raw materials and concentrated sulfuric acid as a medium. In this chlorination reaction, the methyl group and the sulfonic acid group have the same positioning effect, so the chlorination can only occur at the ortho position of the methyl group, so the formation of isomers is not considered. The chlorination of p-toluenesulfonic acid belongs to the substituting halogenation on the aromatic ring, and the most important factor affecting the formation of m-chloro-p-toluenesulfonic acid is the control of the chlorination depth and reaction temper...

AI Technical Summary

Problems solved by technology

[0003] The existing 4-methyl-5-chlorobenzenesulfonic acid production process at home and abroad generally adopts kettle type or tower type reaction device. This type of reactor has many obvious defects, such as poor gas-liquid mixing effect, low uniformity, The chlorine utilization rate is not high, the product yield is low, etc.

Chinese patent CN109369469A provides a method for preparing CLT acid chlorides by continuous reaction in a spray loop. Although the method utilizes an injector to mix chlorine gas with materials, the residence time of chlorine gas is short, and the reaction of chlorine gas is not complete, resulting in the generation of chlorine gas. waste

[0005] For traditional jet loop reactors, the aspect ratio of the loop reactor usually needs to be more than seven times during the industrial scale-up process. For large-scale loop reactors, too high aspect ratio will make the liquid level too high. High, the flow resistance is too large, the required mass transfer kinetic energy is large, so the energy consumption will increase accordingly, and the mass transfer effect will also be reduced, which will easily cause uneven distribution of the gas phase

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