Method for purifying byproduct hydrogen chloride in fluorinated alkane production

Abstract

The invention relates to a method for purifying a byproduct hydrogen chloride in fluorinated alkane production. The method comprises the following steps: sequentially passing the byproduct in fluorinated alkane production through a first absorption tower filled with an activated carbon absorbent, a second absorption tower filled with an aluminum oxide absorbent, and a third absorption tower filled with a molecular sieve absorbent and a silica gel absorbent, so as to obtain a hydrogen chloride product, wherein the weight content of the hydrogen chloride in the hydrogen chloride product is less than 5 ppm, the weight content of an organic fluoride is less than 50 ppm, and the weight content of water is less than 50 ppm. The purified hydrogen chloride gas can be used for synthesizing products such as vinyl chloride monomers, metal chloride, chlorocarbon and trichlorosilane, and raw materials for preparing chlorine in a oxychlorination mode, the application range of the byproduct hydrogen chloride gas is widened, the additional value is improved, and compared with the conventional process that the hydrogen chloride gas is converted into a byproduct hydrochloric acid, the method has remarkable economic benefits.

Description

technical field [0001] The invention relates to a method for purifying by-product hydrogen chloride in the production of fluorinated alkanes. Background technique [0002] Chlorofluorocarbons (CFCs) are widely used as refrigerants, aerosols, foaming agents, solvents, cleaning agents, fire extinguishing agents, etc., but CFCs are ozone-depleting substances with high greenhouse effect value, in order to protect the ozone layer , the United Nations Program adopted the "Montreal Agreement", which stipulates that CFCs must be phased out and their substitutes must be found. HFC-134a (1,1,1,2-tetrafluoroethane) is considered to be an ideal and environmentally friendly substitute for CFC-12 (difluorodichloromethane). [0003] Vapor-phase synthesis using TCE as raw material is currently the most advanced production process for HFC-134a. This process mainly takes place in the following two-step reactions: [0004] Cl 2 C=CHCl+3HF→CF 3 CH 2 Cl+2HCl [0005] CF 3 CH 2 Cl+HF→CF ...

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Problems solved by technology

[0008] However, there is still no method suitable for the purification of by-product hydrogen chloride in the production of fluorinated alkanes, and the above methods have not paid much attention to the removal of organic fluoride in hydrogen chloride. In fact, in high-end applications of hydrogen chloride such as chlorine Ethylene monomer, trichlorosilane, etc. have relatively high requirements for hydrogen fluoride and organic fluoride, because the existence of these impurities may cause catalyst deactivation, poisoning and other adverse effects during the reaction process

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