Progress in development and application of solid-state NMR for solid acid catalysis

Abstract

Solid acid catalysts have been widely used in petrochemical industry and their catalytic activities are normally dictated by their acidities. Unlike conventional acidity characterization techniques such as titration, infrared, or temperature-programmed desorption, detailed acid features of solid acids, such as type, distribution, concentration, and strength of acid sites may be attained by advanced methods involving pertinent probe molecules and state-of-the-art solid-state nuclear magnetic resonance (SSNMR) techniques, i.e. double resonance and two-dimensional correlation spectroscopies. In addition, in situ solid-state NMR method is capable of probing the guest/host properties of the reactant at the active centers of the catalysts as well as the intermediate species formed during conversion. It provides direct experimental evidence for exploring the mechanism of catalytic reaction. In this report, the fundamental theory and the recent developments in solid-state NMR are reviewed with specific focus on relevant applications in structure and acidity characterization of solid acid catalysts and catalytic mechanisms.