Desorption technique for methylbenzene in tail gas from benzyl chloride preparation

Abstract

The invention discloses a toluene desorption process in tail gas produced in the benzyl chloride production, which adopts benzyl chloride as a toluene absorbent to input the tail gas produced in the benzyl chloride production to an absorbing tower from the bottom part, a benzyl chloride liquid flows out through the bottom part of the absorbing tower and enters a desorbing tower after being preheated, the toluene obtained after atmospheric distillation operations in the desorbing tower is directly input to the benzyl chloride production, the benzyl chloride liquid flowing out from the bottom part of the desorbing tower undergoes multi-level cooling and is fed to the absorbing tower from the top part so as to spray and absorb the toluene in the tail gas produced in the benzyl chloride production, as well as enabling the desorption process to form the absorption and desorption cycling production. The process can effectively recover the toluene in the tail gas produced in the benzyl chloride production, and make the toluene be directly used in the benzyl chloride production, thereby reducing the product consumption of benzyl chloride production, product costs, discharge of pollutant toluene and the environmental pollution, and the process also greatly improves the product quality of byproduct hydrochloric acid.

Description

technical field [0001] The invention relates to a production process of benzyl chloride, which is a process for desorbing toluene in the tail gas of benzyl chloride production. Background technique [0002] The production method of benzyl chloride usually adopts a batch production method, that is, the raw material toluene is transported to the chlorination kettle through a toluene pump for feeding, and then the materials in the kettle are heated with heat transfer oil. When the materials in the kettle boil, the toluene gas begins to flow along the tower The internal rise is cooled by the condenser and then returned to the tower. During the rising process of the toluene gas, under the irradiation of the light lamp outside the tower, the toluene gas and the chlorine gas undergo a substitution reaction to produce benzyl chloride. As the reaction continues, the content of benzyl chloride in the kettle continues to increase. When it reaches about 95%, the material in the kettle ...

AI Technical Summary

Problems solved by technology

[0003] Although the above-mentioned intermittent production mode of benzyl chloride has many advantages, the toluene in the hydrogen chloride tail gas produced in the production of benzyl chloride cannot be reclaimed, which increases product consumption and product cost; , which also affects the product quality of hydrochloric acid

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