Chapter One - Recent Advances of Solid-State NMR Studies on Zeolites

Abstract

Solid-state nuclear magnetic resonance (NMR) is a well-established tool for the structural characterization and dynamics study of various multifunctional materials. This review intends to cover the recent process for versatile solid-state NMR studies of topology structures, crystallization processes, host–guest interactions, acidities and catalytic reaction mechanisms of various zeolites. New insights into the relationship between zeolite structures and properties at the atomic level could benefit a lot from the new developments of solid-state NMR methodology and density functional theoretical (DFT) calculation. The spatial connections, distance information and anisotropic chemical shifts of silicon sites determined by 29Si magic angle spinning (MAS) NMR can serve as structural constraints to resolve the topology structure of zeolites. 129Xe NMR can be employed to investigate the cage and channel structure and communication in zeolites. The host–guest interactions between zeolite frameworks and confined molecules have been characterized by two-dimensional heteronuclear correlation experiments. The acidity property of zeolites (including acid type, strength, concentration as well as distribution) can be well understood through the combination of solid-state NMR probe molecule technique and DFT calculation. In particular, information about spatial proximities among various acid sites in zeolites is available from two-dimensional double quantum MAS NMR experiments. The crystallization and catalytic reaction mechanisms can be elucidated by monitoring the evolution of crystallization and reaction processes, respectively, through solid-state NMR spectroscopy.