Thermogravimetric studies of ion exchanged forms of zeolites X and Y

Abstract

A thermogravimetric study of some hundred homo-ionic and mixed ionic forms of zeolites X and Y has been made over the temperature range 25 to 1 000°C from which water contents, and hydroxyl group concentrations have been obtained. From a knowledge of the location of the cations derived from the Szilard–Chalmers recoil studies many interesting correlations and features of the cationic forms of these zeolites have been obtained. The density of zeolitic water has been found to be higher than normal water. Dehydroxylation occurs abruptly at around 520°C in the Y zeolites but not in the X zeolites. The temperature at which this abrupt dehydroxylation reaction commences is found to be dependent on the concentration of hydroxyl groups, on the cations present in the zeolites and on the location of the cations in the zeolites.