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CHARACTERIZATION OF H-Y AND CR-Y ZEOLITE CATALYSTS DURING THE OXIDATIVE DESTRUCTION OF CFC11 AND CFC12
Karmakar, S. AND H. L. Greene. CHARACTERIZATION OF H-Y AND CR-Y ZEOLITE CATALYSTS DURING THE OXIDATIVE DESTRUCTION OF CFC11 AND CFC12. JOURNAL OF CATALYSIS 148(2):524-533, (1994).
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 degrees C and 500 h-1 space 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 HC1 produced during the destruction of CFCs into C12, thereby restoring tyhezeolite acid sites.