Technique for preparing monochlorodifluoromethane by decomposing trifluoromethane

Abstract

The invention provides a technique for preparing monochlorodifluoromethane by decomposing trifluoromethane. The technique comprises the steps of: feeding the raw materials trifluoromethane and methane chloride into a reactor filled with a catalyst in the mol ratio of 0.1-10, and carrying out a decomposition reaction at a temperature ranging from 150 to 350 DEG C for 3-30 seconds to obtain a mixture of trifluoromethane, methane chloride, dichloromonofluoromethane and monochlorodifluoromethane; obtaining monochlorodifluoromethane directly through separation, reacting dichloromonofluoromethane separated out with hydrogen fluoride to produce monochlorodifluoromethane, and separating out and recovering trifluoromethane and methane chloride in the mixture as the reaction mixture continuously. The method has the advantage that the harm on the environment caused by trifluoromethane emission is greatly avoided.

Description

technical field [0001] The invention relates to a process for preparing difluorochloromethane, in particular to a process for preparing difluorochloromethane by cracking trifluoromethane. Background technique [0002] Trifluoromethane (CF3H, HFC-23) is a by-product of the reaction of HF and chloroform to generate chlorodifluoromethane (HCFC-22), and its content in the generated HCFC-22 is less than about 3wt%, but due to HCFC- 22 itself is the main source for the manufacture of perfluoroolefins such as tetrafluoroethylene (TFE). The global annual production of HCFC-22 is very large, and the annual production of trifluoromethane reaches tens of thousands of tons. Trifluoromethane is a greenhouse gas with a very high global warming potential and a long lifespan. The by-product trifluoromethane needs to be utilized or treated to avoid environmental problems caused by emission. [0003] At present, the treatment methods of trifluoromethane are divided into two types: reuse and ...

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Problems solved by technology

However, this method can be seen in the example of the co-cracking of trifluoromethane and HCFC-22. The conversion rate of HCFC-22 is 100%, but the yield of pentafluoroethane is 60%, and 40% of the by-products are useless products. , needs to be treated separately, and a new and relatively large amount of by-products are produced in the method itself for dealing with HFC-23

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