The thermal stability of faujasites with different Si Al ratios

Abstract

The thermal stability of a series of sodium and cation exchanged faujasites, with Si Al ratios ranging from 1.2-7.0 has been determined. The thermal stability of low Si Al ratio faujasites was found to be more sensitive to the cationic form and the degree of exchange than that of the high Si Al ratio faujasites. A redistribution of sodium ions and polyvalent ions occurred among the cation sites during the d.t.a. analysis. The number of polyvalent ions locked in the sodalite cages and hexagonal prisms was found to decrease as the Si Al ratio increased. A series of La3+Ca2+ exchanged faujasites showed nearly the same crystal collapse temperatures for a given Si Al ratio as the corresponding La3+ exchanged Na+ faujasites. © 1986.