Abstract
There are many kinds of siliceous zeolites with SiO2/Al2O3≥10 synthesized by using organic templates. Some types of siliceous zeolites like MFI, MOR, FER and HEU can be synthesized without organic templates and they are used mainly as adsorbents and catalysts. Crystallization method and conditions controlling the crystalline properties of these siliceous zeolites are described.
The results of formation mechanism of zeolitic framework, and the correlation between the aluminosilicate molecules in the reactant mixture of zeolite synthesis and the pseudo-aluminosilicate molecules in the framework of zeolite are presented.
Distribution of Al atoms in the zeolitic framework affect not only its physicochemical properties but also its adsorptive and catalytic properties. The determination method of Al atoms in MOR type zeolite is briefly shown, and the newly founded rule known as “2A1/5-ring avoidance rule” complementing the Loewenstein's rule is also explained.
