Dechlorohydrogenation of CFC 113 (CCl₂FCCIF₂) over Metal Catalysts Supported on Fluorides

Abstract

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. O ver Ni/CeF₃, Ni/LaF₃, and Ni/CaF₂ catalysts, C₂C1F₃( I ) and CH, 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/CeF ₃and Pd/LaF₃ and the conversion increased with increasing temperature. The conversion gave a maximum of 85% at 300°C and a minimum of 10-45% at 450-500 °C and then increased again with increasing temperature. CF₃CC1H₂(II) and CF₃CC1₂H(II) were formed at <350°C and the selectivity of (IV) increased to 90% at 550°C from 50% at 150°C over Pd/CeF ₃. Compounds (II) +(IV), C₂F₃H, and ( I ) were formed successively with increasing temperature over Pd/LaF3. Pd/MnF2 was less active for the reaction. Compounds (II)+(IV) and CFHCFH(V) were major products at <250°C and at 300-500°C, respectively, over Pt/C eF3. (II) and (V) were produced slectively at <250 °C and 250-500°C over Pt/LaF₃, respec tively. A ctivity of Pt/MnF₂ was relatively low, and the high selectivity, 80-400%, was maintained at all reaction temperatures. Compound( I) was a major product at>350°C over Au/MnF 2and Au/CeF₃. No changes in acitivity and selectivity were observed after 55 h at 300°C over Ni/CaF ₂. j9-PbF₂ changed into PbC1₂ during the reaction, however, the other fluorides reacted with neither CFC 113 nor supported metals. Specific surface areas of Pd/CeF₃ and Au/CeF ₃ increased after the reaction. Dispersion of Pd increased during the reaction over fluoride supports.