LUMINESCENCE STUDIES ON INTRAZEOLITIC MIGRATION OF TB(III) IONS BY THERMAL TREATMENTS .1. FAU-TYPE ZEOLITES

Abstract

It is observed from the luminescence measurements that the intrazeolitic migration of Tb(III) ions arising from thermal treatments in FAU-type zeolites is strongly dependent on the framework Si/Al ratio. For a low-silica FAU zeolite (Si/Al = 1.37) most of the Tb(III) ions exchanged into supercages begin to migrate directly to hexagonal prisms at 423 K without staying at sodalite cages; by contrast, the cations in a high-silica FAU zeolite (Si/Al = 3.40) migrate first to sodalite cages at 373 K and in turn to hexagonal prisms at temperatures higher than 373 K.