The gas-phase reaction of a mixture of waste refrigerant gases, namely R22 (CHCIF₂), R12 (CCI₂F₂) and R134a (CH₂FCF₃) with CH₄ has been investigated over the temperature range of 873–1133 K. The investigation was undertaken as an initial assessment of the viability of this process as a treatment option for waste mixtures of hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFC), chlorofluorocarbons (CFCs) and as a potential route for the synthesis of CH₂=CF₂ (VDF). During the reaction, CH₂=CF₂ is observed as the major product formed and a 43% selectivity to CH₂=CF₂ is obtained at 1073 K. A detailed mechanism is developed based on the mechanistic analysis from kinetic modeling, with the initiation reaction involving the formation of CI radicals from CCI₂F₂. Good agreement is achieved between the predictions and experimental results. Based on a mechanistic analysis, a summary of the major reaction pathways is proposed, which is consistent with the experimental observations.
Journal of Hazardous Materials Vol. 184, Issue 1-3, p. 696-703