Oxidative decomposition of dichlorodifluoromethane (CFC-12) in the presence of butane over Tungsten(VI) oxide catalysts supported on alumina-zirconia

The oxidative decomposition of dichlorodifluoromethane (CFC-12) in the presence of butane was investigated with tungsten(VI) oxide catalyst supported on alumina-zirconia. In this reaction, it is considered that CFC-12 might react with water formed by the combustion of butane at high temperatures above 773 K, and that most of CFC-12 might react directly with oxygen at low temperatures below 723 K. The CFC-12 conversion over the tungsten(VI) oxide catalyst decreased with the passage of time on stream at low temperatures below 673 K. This deactivation of the catalyst was attributed to the coke deposition on the acid sites of the catalyst as well as to the fluorination of the acid sites. The CFC-12 conversion at 4 h on stream became higher when the catalyst was loaded with platinum or palladium, but the butane conversion was not changed by loading. The amount of the coke deposited on platinum- or palladium-loaded tungsten(VI) oxide catalysts, which exhibited a high CFC-12 conversion at 4 h on stream, was very small. Accordingly, the depression of the catalyst deactivation might be caused by the combustion of the coke deposited on the acid sites due to the catalysis of platinum and palladium.