The ‘Open’ Site of Lewis Acid Zeolites for Meerwein‐Ponndorf‐Verley‐Oppenauer Reactions in Biomass Catalysis

Abstract

Heteroatom zeolites are efficient catalysts for activating oxygenates in Meerwein‐Ponndorf‐Verley‐Oppenauer (MPVO) reactions, due to the unique Lewis acid character of their tetrahedral heteroatom metal sites. Such Lewis acid zeolites, especially heteroatom Beta zeolites, are intensively investigated with increasing attention in the valorization of biomass‐derived oxygenates. Herein, we first briefly review the recent development and advantage of Lewis acid zeolites for MPVO reactions involved in biomass valorization, majorly based on the selected case studies of the most representative heteroatom Beta zeolites. Increasing recognization of the open framework sites as the intrinsic active sites for Lewis acid zeolites in MPVO reactions has been discussed, with static and dynamic viewpoints. Furthermore, the recent progress on the development of characterization technologies applied in recent the state‐of‐the‐art showcases of identification and quantification of open sites, has been assessed, with a special focus on indirect detection using probe molecules and direct detection approaches. Future opportunities and challenges regarding the development of complimentary in situ characterization technologies and in‐depth understanding of the true nature of active sites and correlative mechanisms are examined for the ultimate goal of providing stable MPVO catalysts in biomass valorization.