3.19 Preparation of Basic Zeolite

Abstract Zeolites containing cesium oxide in the cavities were prepared under different conditions to establish the preparative conditions under which the crystalline structures are retained. The types of cesium salt used as ion-exchange and impregnation solution did not affect much the crystallinities of the resulting materials. The most important factor in terms of the retention of the crystalline structure of the resulting zeolites was the presence of water vapor during calcination. In the presence of water vapor, the zeolite structures collapsed at relatively low temperatures. On the bases of 29 Si and 27 AL MAS NMR, it was suggested that the collapse of the zeolite structures occurs by breaking of Si-O-Si bonds rather than AL-O-AL bonds for K ion-exchanged zeolite.