Existence of Colloidal Primitive Building Units Exhibiting Memory Effects in Zeolite Growth Compositions

Abstract

This study focuses on the clear, stable mother liquors obtained after completion of crystallization of nanocrystalline sodalite, zeolite A, and zeolite Y. Characterization of the freeze-dried mother liquors by high-resolution transmission electron microscopy showed regions of crystallinity for both zeolites A and Y, and ∼5 nm regions of crystallinity could be identified in zeolite Y. Upon adding the mother liquor to nutrient solutions of aluminates and silicates, it was found that the mother liquor could direct formation of the corresponding framework, thereby manifesting a memory effect. Dynamic light scattering studies showed that there were units present in the mother liquors that grew into crystals at a faster rate than the parent compositions used to generate the mother liquors. We propose that the mother liquors recovered after crystallization contain primary structural units having memory of the zeolite formed and that these units can assemble to form viable nuclei if provided with a source of nutr...