The gas-phase reaction of CH₄ and CHC1F₂ (HCFC-22, R22) has been studied in an alumina tubular reactor at atmospheric pressure and in the temperature range of 673−1073 K. The motivation of the investigation is to assess this process as a potential route for the treatment of CHC1F₂, as well as a technology for the synthesis of CH₂═CF₂ (vinylidene fluoride, VDF). Under the conditions studied, the major products are C₂F₄, CH₂═CF₂, HF, and HCl. Minor products detected include C₂HF₃, C₂H₂, CHF₃, C₂H₃F, C₂H₂F₄, CH₂F₂, C₃F₆, CH₃Cl. A mechanistic interpretation of the results is proposed, including the reactions involved in the initial decomposition of CHClF₂, those contributing to the activation of CH₄ and developing the pathways leading to the formation of product species. The result of changing feed ratio experiments is consistent with the reaction mechanism developed. The introduction of small amounts of O₂ improves the conversion of CH₄ and formation of CH₂═CF₂ markedly.
Industrial and Engineering Chemistry Research Vol. 49, Issue 13, p. 6010-6019