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

Abstract

A detailed reaction mechanism is developed and used to model experimental data on the pyrolysis of CHF 3 and the non-oxidative gas-phase reaction of CHF 3 with CH 4 in an alumina tube reactor at temperatures between 873 and 1173 K and at atmospheric pressure. It was found that CHF 3 can be converted into C 2F 4 during pyrolysis and CH 2 CF 2 via reaction with CH 4. Other products generated include C 3F 6, CH 2F 2, C 2H 3F, C 2HF 3, C 2H 6, C 2H 2 and CHF 2CHF 2. The rate of CHF 3 decomposition can be expressed as 5.2 × 10 13 [ s − 1 ] e − 295 [ kJ mo l − 1 ] / R T . During the pyrolysis of CHF 3 and in the reaction of CHF 3 with CH 4, the initial steps in the reaction involve the decomposition of CHF 3 and subsequent formation of CF 2 difluorocarbene radical and HF. It is proposed that CH 4 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.