In-situ two-dimensional MAS NMR spectroscopy for heterogeneous catalysis.

In-situ magic-angle spinning (MAS) NMR has emerged as a pivotal technique for elucidating catalytic reaction mechanisms and dynamic structural evolution of catalysts at the atomic level under working conditions. This review summarizes the applications of in-situ MAS NMR in the investigation of catalytic reactions and crystallization processes of catalysts, highlighting its unique capability in real-time monitoring of transient species and structural transformations. Recent advances in specialized NMR hardware (e.g., high-temperature and high-pressure (HTHP) rotors) and pulse sequences (e.g., fast 2D acquisition) have significantly enhanced the sensitivity and acquisition efficiency, enabling unprecedented mechanistic insights via in-situ charactorization. We showcase the latest breakthroughs in catalysis research utilizing in-situ MAS NMR spectroscopy, including methanol conversion, zeolite synthesis, and surface reaction dynamics. This review also emphasizes the transformative integration of HTHP in-situ MAS NMR with fast 2D correlation spectroscopy particularly for quadrupolar nuclei. The importance of combining the hardware (HTHP rotors) and software (pulse sequences) methods is highlighted in developing in-situ MAS NMR, and the key directions for future methodological innovations are discussed.