Water in ion-exchanged L, A, X and Y zeolites: a heat of immersion and thermogravimetric study

Abstract

Heats of immersion in water of zeolites L, A, X and Y enriched with an extensive range, including transition metal species, of uni-, di- and trivalent cations have been measured and heats of solvation of the cations by the anhydrous zeolite frameworks calculated. Differential heats of water sorption as a function of coverage in Co–A, Zn–A, Co–Y and Zn–Y have been determined. Differential thermogravimetric analysis of the zeolites is discussed. The heat data are interpreted in the light of the available information on cation location and with reference to the unit cell compositions. It is shown that the Born ion-solvation model can form a reasonable basis for the interpolation of heats of immersion and energies of solvation of the cations by the anhydrous zeolite framework.