| Abstrakt: |
The long term stability-deactivation characteristics of two Y zeolite catalysts, namely H-Y and cation exchanged Cr-Y, were studied during the oxidative destruction of CFC11 and CFC12 feeds. Experiments were carried out at 300°C and 5000 h−1space velocity. Properties of the catalysts including activity, selectivity, surface area, acidity, composition, and crystallinity were determined as a function of reaction time. Comparison of these properties with time indicated a significantly higher degree of deactivation for the H-Y catalyst than for the Cr-Y catalyst. The most probable reasons for the improved stability characteristics of the Cr-Y catalyst were the greater stability of the zeolite matrix due to multivalency of the exchanged Cr cation, and also the Deacon reaction characteristic of Cr3+, which converted HCl produced during the destruction of CFCs into Cl2, thereby restoring the zeolite acid sites. |
