Pd/Alumina Catalysts for Beneficial Transformation of Harmful Freon R-22

Chlorodifluoromethane (R-22), the most abundant freon in the atmosphere, was subjected to successful hydrodechlorination in the presence of palladium supported on gamma-alumina, at a relatively low reaction temperature (180 & DEG;C). The combination of catalytic actions of alumina (performing freon dismutation) and Pd nanoparticles (catalyzing C-Cl bond splitting in the presence of hydrogen) results in the transformation of freon into valuable, chlorine-free products: methane and fluoroform, the mixture of which is used in plasma etching of silicon and silicon nitride. Very highly metal dispersed Pt/Al2O3 catalysts, with metal particles of ~1.3 nm in size, are not as effective as Pd/Al2O3, resulting in only partial dechlorination. A long-term dechlorination screening (3-4 days) showed good catalytic stability of Pd/alumina catalysts.