Site group interaction effects in zeolite Y. Part 3.—K–Na equilibrium

Abstract

A selectivity study has been made on the potassium–sodium equilibrium in zeolite Y in the supercages, using cesium as a reference cation, and in the small cages, by blocking the supercages with either cesium or cobalt ions. The overall free energy effect for the potassium–sodium exchange in the whole crystal differs from the value predicted on the basis of data for supercages and small cages. Site heterogeneity has been demonstrated in the small cages on the basis of selectivity reversals which are dependent on the nature of the ions in the supercages. The observed effects are analysed in terms of interactions between supercage and small cage.