Fourier transform infrared study of 1,1-dichlorotetrafluoroethane adsorption on an alumina-supported Pd catalyst

An FTIR investigation of CF3CFCl2 adsorption on 5% Pd/gamma-Al2O3 at room temperature shows that three types of surface species form. Two of the species are identified as trifluoroethylidyne (CF3CE) and the third species is assigned to tetrafluoroethylidene (CF3CF=). All three species are on the metal sites, not on the gamma-Al2O3. The surface of the reduced fresh catalyst favors the formation of trifluoroethylidyne species. However, CF3CFCl2 adsorption on a catalyst preexposed to the CFC + H-2 mixture at 473 K for 1 h, followed by reduction with H-2 at 573 K for 1 h, results in the predominant formation of CF3CF=. Both surface CF3CF= and CF3C drop species readily interact with H-2 at room temperature to form CF3CFH2 and CF3CH3.