Applications of in-situ solid-state nuclear magnetic resonance (ssNMR) in methanol to olefins (MTO) reaction

Abstract

The methanol-to-olefins (MTO) reaction offers an alternative pathway for the production of low-carbon olefins from non-oil feedstocks. Fundamental research has been impeded by a lack of comprehensive understanding of its underlying mechanism, despite the significant progress made in industry. In-situ solid-state nuclear magnetic resonance (ssNMR) spectroscopy has emerged as a pivotal tool, offering crucial insights into key species under real-time operando conditions. Furthermore, the host–guest interaction between zeolites or surface species residing on zeolites and the reactant/active intermediates is revealed by the combination of in-situ¹³C MAS NMR and 2D correlation spectroscopy. Moreover, recent technological advancements in hyperpolarization (HP) methods, including HP ¹²⁹Xe NMR and dynamic nuclear polarization (DNP), have significantly improved the sensitivity of ssNMR, enabling detailed structural and kinetic analysis as well as the detection of trace species. In this feature article, we summarized recent advancements in (in-situ) ssNMR spectroscopy applied to MTO reaction processes, encompassing mechanistic investigations at various stages and the intricate host–guest interactions. These theoretical insights into the dynamic evolution of MTO reactions lay a solid foundation for the optimization of catalytic processes and the development of efficient catalysts, thereby advancing the techniques towards more sustainable and economical production route for olefins.