PALLADIUM-CATALYZED HYDROGENATION WITHOUT HYDROGEN - THE HYDRODECHLORINATION OF CHLOROFLUOROCARBONS WITH SOLID-STATE HYDROGEN OVER THE PALLADIUM(111) CRYSTAL-SURFACE AND ITS IMPLICATIONS

The hydrogenation of chlorofluorocarbons (CFC's, 1,1-dichlorotetrafluo roethane, CCl2F-CF3) was found to be positive 1/2 order in hydrogen pr essure over palladium foil while it was zero order in hydrogen pressur e over palladium single crystals regardless of their orientation ((111 ), (100)). When hydrogen was completely removed from the gas phase, hy drogenation continued for about 10(4) turnovers over palladium single crystals which were pre-exposed to hydrogen. Solid state hydrogen, sto red in the bulk of a palladium single crystal, was found to be respons ible for the hydrodechlorination of CCl2 F-CF3 in the absence of gas p hase hydrogen. Lower reaction rates and increased selectivity for over hydrogenation to produce CH3-CF3 indicate that the nature of hydrogena tion with solid state hydrogen in palladium is different from hydrogen ation with gas phase hydrogen. The use of solid state hydrogen for var ious chemical processes instead of gas phase hydrogen has advantages t hat are enumerated.