Kenyaite Pillared

Figure 6 A conq)arison betweeen the activities of two different layered silicates, magadiite and kenyaite, as a fimction of their interlayer species. Alumina pillared kenyaite appears to have significantly more activity than a comparable pillared magadiite. This indicates a sensitivity towards the layered structure.

Hitherto the most successful pillaring has been carried out on smectite type clays. The original research on pillaring included several series of unsuccessful experiments on mica, vermiculite and the sheet silicic acid minerals magadiite, silhydrite and kenyaite. Recently renewed attention has focused on these and other alternative sheet structures. They include rectorite, zirconium phosphates, tetrasilicic micas, hydrotalcites and silicic acids, the general structural features of which are shown in Figure 4. 

TABLE 5 Physical Properties of Silica-Pillared Magadiite and Kenyaite... 

Finally, the acid- or base-catalyzed reaction of hydrolysis and condensation polymerization of TEOS into a layered silicate gallery could affect the physical properties of silica-pillared magadiite and kenyaite. The samples that were silica-pillared by acid- and base-catalyzed reactions show a large increase in basal spacing. Also, they exhibit relatively narrow pore size distributions and show high surface areas, depending on the type of catalyst and layered silicate. These results indicate that variations in the conditions of gelation contribute to the improvement in the physical properties of silica-pillared molecular sieves. 

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