Method for recycling sulfur dioxide in thionyl chloride production

Abstract

The invention belongs to the technical field of thionyl chloride production, and mainly relates to a method for recycling sulfur dioxide in the production of thionyl chloride. The method comprises the following steps: (a) the tail gas produced by the sulfur compounding process and the distillation process enters the tail gas condenser to condense the sulfur dioxide gas therein; (b) the condensed sulfur dioxide liquid enters the sulfur dioxide recovery tank; (c) adopts a sulfur dioxide vaporizer The recovered sulfur dioxide liquid is vaporized to a pressure slightly higher than the pressure of the reaction system and then returned to the reaction system for recycling. The invention greatly improves the utilization rate of sulfur dioxide and product yield, and has small equipment investment and simple operation.

Description

technical field [0001] The invention belongs to the technical field of thionyl chloride production, and mainly relates to a method for recycling sulfur dioxide in the production of thionyl chloride. Background technique [0002] Thionyl chloride (SOCl 2 ) is an important fine chemical raw material in the development of my country's national economy. In the "National High-tech Product Catalogue" issued by the former State Science and Technology Commission, "pharmaceuticals, veterinary drugs, pesticides, intermediates and products" are listed as high-tech products. Domestic production of thionyl chloride includes chlorosulfonic acid method, co-production method, sulfur trioxide method and sulfur dioxide gas phase method. The main raw material for the production of thionyl chloride by sulfur dioxide gas phase 2 , Cl 2 , S 2 Cl 2 , and its reaction equation is: S 2 Cl 2 +Cl 2 →SCl 2 SO 2 +Cl 2 +SCl 2 →SOCl 2 [0003] Part of the incompletely reacted tail gas in th...

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Problems solved by technology

[0003] Part of the incompletely reacted tail gas in the production process enters the sulfur compounding section with the crude thionyl chloride product, and its main components are chlorine gas, sulfur dioxide, and a small amount of thionyl chloride vapor, and the remaining tail gas after the chlorine gas is absorbed by sulfur monochloride and Part of the non-condensable gas released during the distillation process is mainly composed of sulfur dioxide and a small amount of thionyl chloride vapor. If these substances are not recycled and directly enter the subsequent tail gas alkali cleaning system, it will not only increase the unit consumption of raw materials in the production process, but also reduce the product yield. , will also increase the consumption of liquid alkali in the tail gas absorption system, which will increase the investment

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