DECOMPOSITION OF CHLOROFLUOROCARBONS ON TIO2-ZRO2

The decomposition of chlorofluorocarbons (CFCs) in the presence of wat er was examined over a variety of solid acid catalysts. The TiO2-ZrO2 catalyst was found to have the highest activity and longest Life among the catalysts examined. The activity of the TiO2-ZrO2 catalysts depen ded upon the content of TiO2. At the contents of TiO2 from 58 to 90 mo le%, the TiO2-ZrO2 catalysts exhibited high activity, and these cataly sts were proven to contain TiZrO4 crystal. From the study of the XRD p eak intensity of the TiZrO4 crystal, it was highest on the TZ-58 which contained 58 mole% of TiO2, and decreased with increasing the content of TiO2. Furthermore, the conversion of CFC113 measured at 673 K was highest at TZ-58, and decreased gradually with increasing TiO2 content , Therefore, the TiZrO4 crystal influences the activity of decompositi on of CFC113. However, the TiO2-ZrO2 catalyst was gradually deactivate d during the reaction due to the elimination of titanium atoms. A good relationship was found between the activity on TiO2-ZrO2 catalyst and bond energy of C-Cl in the compounds of chlorofluorocarbons and hydro chlorocarbons, suggesting that the rate controlling step was the cleav age of C-Cl bond.