Dechlorohydrogenation of CFC 113 (CCI₂FCCIF₂) over Metal Catalysts Supported on Fluorides

Hydrodechlorination, dechlorohydrogenation, and isomerization of CFC 113 took place over Ni, Pd, Pt, Au catalysts supported on fluorides at 200—550 °C in the presence of hydrogen. Over Ni/CeF_3j Ni/LaF₃, and Ni/CaF₂ catalysts, C₂C1F₃(I) and CH₄ were formed selectively at <350°C and at >450 °C, respectively. Compound (I) was a major product at 250—550 °C over Ni/PbF₂ and Ni/MnF₂ catalysts. CFC 113 was converted at > 150-200 °C over Pd/CeF₃ and Pd/LaF₃ and the conversion increased with increasing temperature. The conversion gave a maximum of 85% at 300 °C and a minimum of 10∼15% at 450∼500 °C and then increased again with increasing temperature. CF₃CC1H₂(II) and CF₃CCl₂H(III) were formed at <350 °C and the selectivity of (F) increased to 90% at 550 °C from 50% at 150 °C over Pd/CeF₃. Compounds (II) + (F), C₂F₃H, and (I) were formed successively with increasing temperature over Pd/LaF₃. Pd/MnF₂ was less active for the reaction. Compounds (II) + (III) and CFHCFH(V) were major products at <250°C and at 300—500 °C, respectively, over Pt/CeF₃. (IE) and (V) were produced slectively at <250 °C and 250-500 °C over Pt/LaF_3} respectively. Activity of Pt/MnF₂ was relatively low, and the high selectivity, 80—100%, was maintained at all reaction temperatures. Compound(I) was a major product at >350°C over Au/MnF₂ and Au/CeF₃. No changes in acitivity and selectivity were observed after 55 h at 300 °C over Ni/CaF₂. β-PbF₂ changed into PbCl₂ during the reaction, however, the other fluorides reacted with neither CFC 113 nor supported metals. Specific surface areas of Pd/CeF₃ and Au/CeF₃ increased after the reaction. Dispersion of Pd increased during the reaction over fluoride supports.