MECHANISM OF ZEOLITE FORMATION - SEED GEL INTERACTION

The mutual interactions between zeolite Y seed crystals and amorphous aluminosilicate gels in influencing zeolite synthesis has been examined. Reactant compositions that result in the synthesis of faujastic- and gismondine-type frameworks is the focus of this study. A reactor system in which seed crystals and gel are seperated by a 0.2 mum membrane has been used for the synthesis experiments. The membrane allows for ready passage of soluble species, while keeping the solids separate. The results indicate that the seed crystals modify the crystallization process if they are in physical contact with the gel, but do not influence it if they are kept separated via the membrane. Thus, it appears that the viable nuclei generated either from the seed or the gel do not travel readily through the 0.2 mum membrane, suggesting a minimal size of 2000 angstrom. But, at the same time, crystal growth occurs readily on both sides of the membrane, suggesting incorporation of solution species that travel freely across the membrane.