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

Abstract

Chlorodifluoromethane (R-22), the most abundant freon in the atmosphere, was subjected to successful hydrodechlorination in the presence of palladium supported on γ-alumina, at a relatively low reaction temperature (180 °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.

Advances in morphology-controlled alumina and its supported Pd catalysts: synthesis and applications

“…Karpinski et al reported successful hydrochlorination of freon (chlorodifluoromethane) at a relatively low reaction temperature (180 °C) using the alumina-supported Pd catalyst. 182 The combination of catalytic actions of alumina, which performs freon dismutation, and Pd nanoparticles, which catalyze C–Cl bond splitting in the presence of hydrogen, results in the transformation of freon into valuable, chlorine-free products (methane and fluoroform), as well as excellent catalytic stability (as shown in Fig. 26A).…”