Effects of exchangeable cations on the adsorption properties of Na+ mordenite

Abstract

Na⁺ mordenite has been progressively exchanged with various cations (Cs⁺, K⁺, Li⁺, Ba²⁺, Mg²⁺, La³⁺); simultaneously, variations in the pore volume have been measured by nitrogen adsorption as a function of the degree of exchange. The variations are pronounced and are very dependent on the nature and on the degree of exchange of the permuted cations. These results cannot be interpreted on the basis of the variation of the volume of exchanged cation or on the modifications of the crystal framework. The distribution of aluminium in the zeolite framework has been determined to estimate the density and predict the selectivity of each potential site towards a cation. The position of the cations determines the pore volume that is accessible to nitrogen.