EFFECT OF WATER VAPOR PRESSURE ON DE- AND REHYDRATION OF ZEOLITE ROCKS.

This paper investigated the effect of water vapor pressure on de- and rehydration of zeolite rocks and their cation exchanged forms. Mordenite tuff and clinoptilolite tuff from Japan was used as starting materials from which Na-, K-, Ca-, NH//4- and H-exchanged forms were prepared by cation exchange treatment. They were examined by X-ray, IR and thermal techniques. The wave number of the IR absorption band at about 3400 cm** minus **1 due to OH stretching vibration shifts linearly with increasing amount of cations. High temperature XRD reveals that the framework structures of the exchanged forms are maintained up to 450 degree C. TG curves obtained in an atmosphere of controlled P//H//2//O from 0 to 70. 6 mmHg indicate an hysteresis effect between de- and rehydration processes. In the case of H forms, de- and rehydration are not influenced by water vapor pressure and no hysteresis effect is observed above 200 degree C.