Trimethylsilylation of zeolites. Evidence for the presence of adjacent aluminium atoms

Abstract

Trimethylsilylation of the zeolites A, ZK-21, P, and X followed by gas–liquid chromatographic analysis of the volatile silicate fragments obtained has produced size-distribution patterns which show that Loewenstein's rule, which forbids adjacent AlO₄ tetrahedra, is not obeyed in these zeolites. Comparison of the results with calculated size distributions for various alternative arrangements of aluminium atoms indicates that in these zeolites between onethird and one-half of the AlO₄ tetrahedra are linked in pairs.