Co-development of Crystalline and Mesoscopic Order in Mesostructured Zeolite Nanosheets

Abstract

Mesoporous zeolites are a new and technologically important class of materials that exhibit improved diffusion and catalytic reaction properties compared to conventional zeolites with sub-nanometer pore dimensions. During their syntheses, the transient developments of crystalline and mesoscopic order are closely coupled and challenging to control. Correlated solid-state NMR, X-ray, and electron microscopy analyses yield new molecular-level insights on the interactions and distributions of complicated organic structure-directing agents with respect to crystallizing zeolite frameworks. The analyses reveal the formation of an intermediate layered silicate phase, which subsequently transforms into zeolite nanosheets with uniform nano-and mesoscale porosities. Such materials result from coupled surfactant self-assembly and inorganic crystallization processes, the interplay between which governs the onset and development of framework structural order on different length and time scales.