CHARACTERIZATION OF H-Y AND CR-Y ZEOLITE CATALYSTS DURING THE OXIDATIVE DESTRUCTION OF CFC11 AND CFC12

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 5000 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 HCI produced during the destruction of CFCs into Cl2, thereby restoring the zeolite acid sites. (C) 1994 Academic Press, Inc.