CATION LOCATION IN LA,NA-Y ZEOLITES BY 2-DIMENSIONAL NA-23 NUTATION NMR

The variation of the cation distribution with the lanthanum-exchanged level in hydrated La,Na-Y zeolites was clearly monitored by two dimensional nutation sodium-23 NMR, in which the chemical shift and the quadrupole interaction could be separated. From a comparison of Na-23 NMR at different hydrated states and temperatures it is concluded that the mobility of water molecules and sodium ions can be reduced by decreasing sample temperature and the migration of lanthanum ions from supercages to small cages causes the redistribution of sodium ions after dehydration at 350-degrees-C.