Conversion of a CFCs, HFCs and HCFCs waste mixture via reaction with methane

The gas-phase reaction of a mixture of waste refrigerant gases, namely R22 (CHClF2), R12 (CCl2F2) 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 Cl radicals from CCl2F2. 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. (C) 2010 Elsevier B.V. All rights reserved.