Understanding Heterogeneous Catalytic Hydrogenation by Parahydrogen-Induced Polarization NMR Spectroscopy

Abstract

Parahydrogen-induced polarization (PHIP) is an NMR hyperpolarization technique with the ability to increase the NMR sensitivity by serval orders. The generation of hyperpolarization in hydrogenation reactions is associated with a pairwise addition behavior, which is sensitive to the properties of catalysts and the reaction process, making it a powerful tool for the characterization of catalyst properties and elucidation of reaction mechanisms. In this Perspective, we provide an in-depth overview of the heterogeneous PHIP (HET-PHIP) technique and its application in heterogeneous catalytic hydrogenation. The fundamentals of HET-PHIP are introduced. We describe how HET-PHIP can be used to obtain information about the morphology and electronic properties of supported monometallic catalysts, bimetallic catalysts, and zeolites as well as the facet effect and strong metal–support interaction (SMSI) effect in hydrogenation. Advances in the mechanistic understanding of catalytic hydrogenations by using HET-PHIP are discussed with representative work. We propose the current limitations and prospects of the HET-PHIP technique in catalytic hydrogenation reactions.