Catalytic Hydrodechlorination of CFC 113 (CCI₂FCCIF₂)

Pd, Ni, Pt supported on TiO₂ were effective for hydrodechlorination of CFC 113. The reaction took place at >150°C and C₂H₂F₂, C₂F₃C1 and C₂H₂F₂ and C₂H₃F₃ were formed over the catalysts, respectively. C₂F₃C1 was formed over Co/Ti0₂ at 350 °C and the same reaction took place over MnTiO₃ at >500°C. Pd/C tends to substitute hydrogen atoms for chlorine atoms so that CF₂HCFH₂ was formed from CFC 113 with high selectivity of more than 85%. The activities of Rh/C and Pt/C were smaller than that of Pd/C. The addition of 2 mol% of water vapor did not affect the reaction but supressed the formation of CH₄ and promoted the formation of CO at>300°C. Plots of the catalytic activity against the heat of formation of metal chlorides gave a volcano shape. This suggests that the reaction proceeded via chlori-nation and dechlorination of the catalyst surface. MnTi0₃ was so stable that XRD pattern decreased slightly in intensity after the CFC 113-H₂ reaction for 25 h at 550 °C. The structure of Cr₂O₃ was not changed after the reaction at 350 °C for 20 h by XRD.