IR SPECTROSCOPIC STUDY OF THE DYNAMICS OF LATTICE DEALUMINATION OF LAHY ZEOLITES INDUCED BY WATER-VAPOR

The dynamics of dealumination of the framework during treatment of LaH Y zeolites with a different concentration of exchange cations with wat er vapor at 870 and 1070 K were investigated by IR spectroscopy. The p resence of La3+ cations slows dealumination at 870 K, while the effect of exchange cations is less important at 1070 K. The change in the co ncentration of hydroxyl groups, acid sites, and nonlattice aluminum co mpounds was investigated during dealumination. The catalytic propertie s in cracking of hydrocarbons were compared with the acidity of LaNY a nd HY treated with water vapor It was found that for LaHY and HY, zeol ites with a concentration of approximately 30 aluminum atoms in the un it cell exhibit maximum activity in cracking of isooctane.