Water in homoionic and heteroionic mordenites: a calorimetric study. Part 2.—Divalent and trivalent transition metal forms

Abstract

Heats of immersion in liquid water are reported for a range of di- and tri-valent transition metal ion exchanged forms of Na-Zeolon and also for some H-Zeolons. In each case the approximately two exchanged divalent metal cations remain in main channel sites bonded to framework oxygens during dehydration but on immersion in liquid water they rehydrate fully in the main channels; a similar situation is envisaged for the M³⁺ exchanged forms. Using a correlation between heats of immersion for homoionic monovalent exchanged forms and heats of solvation of gaseous ions a method is proposed for obtaining heats of immersion of fully exchanged transition metal forms from experimental data for the partially exchanged zeolites. The correlation is further used to calculate dielectric constants and refractive indices for the exchanged zeolites.