Experimental and chemical kinetic study of the pyrolysis of trifluoroethane and the reaction of trifluoromethane with methane

A detailed reaction mechanism is developed and used to model experimental data on the pyrolysis of CHF₃ and the non-oxidative gas-phase reaction of CHF₃ with CH₄ in an alumina tube reactor at temperatures between 873 and 1173 K and at atmospheric pressure. It was found that CHF₃ can be converted into C₂F₄ during pyrolysis and CH₂=CF₂ via reaction with CH₄. Other products generated include C₃F₆, CH₂F₂, C₂H₃F, C₂HF₃, C₂H₆, C₂H₂ and CHF₂CHF₂. The rate of CHF₃ decomposition can be expressed as 5.2 x 10¹³[s⁻¹]e−295[kJmol⁻¹]/RT. During the pyrolysis of CHF₃ and in the reaction of CHF₃ with CH₄, the initial steps in the reaction involve the decomposition of CHF₃ and subsequent formation of CF₂ difluorocarbene radical and HF. It is proposed that CH₄ is activated by a series of chain reactions, initiated by H radicals. The NIST HFC and GRI-Mech mechanisms, with minor modifications, are able to obtain satisfactory agreement between modelling results and experimental data. With these modelling analyses, the reactions leading to the formation of major and minor products are fully elucidated