Recently, the research team led by Profs. Liu Zhongmin and Wei Yingxu (from National Engineering Research Center of Lower-Carbon Catalysis Technology, Dalian Institute of Chemical Physics(DICP) of the Chinese Academy of Sciences (CAS))published a review article on the dynamic catalytic mechanism of the Methanol-to-Hydrocarbons (MTH) reaction overzeolite catalysts. This review comprehensively summarizes the team's significant research achievements in MTHmechanistic studies. This work is of paramount importance for a profound understanding of zeolite chemistry, particularly the catalytic essence of zeolite under real catalytic reaction conditions.

The Methanol-to-Olefins（MTO）process has successfully bridged coal and petrochemical industries, enabling the efficient and clean utilization of coal resources in China. A profound understanding of the fundamental principles underlying the catalytic reaction process and selectivity control mechanisms is crucial for advancing catalytic materials and process technologies. The Low Carbon Catalysis and Engineering Research Department of DICP has consistently combined fundamental and applied research. Through fundamental studies that unveil microscopic catalytic reaction mechanisms, they provide essential theoretical support for the sustainable development and innovation of technologies.

Zeolites, with their inherent acidity and shape selectivity, play a pivotal role in MTH catalysis. However, the complex characteristics exhibited during the MTH catalytic process, such as dynamic evolution, diverse reaction pathways, and the coupling and decoupling of catalysis and diffusion, pose significant challenges in fully comprehending the MTH catalytic mechanism.The research team has employed advanced techniques, including in situ spectroscopy, isotope labeling, and computational chemistry, to investigate the catalytic process of methanol conversion over zeolites. They have made significant contributions to various aspects, including capturing and identifying active intermediates within zeolite cages/pores (J. Am. Chem. Soc.,2012;Angew. Chem. Int. Ed., 2013；Angew. Chem. Int. Ed., 2017；Nat. Commun., 2020), in situ observation and simulation of the dynamic evolution of catalyst surfaces (ACS Catal., 2018;ACS Cent. Sci., 2021；J. Am. Chem. Soc., 2021；Chem, 2021;Natl. Sci. Rev., 2022), and constructing and simulating elementary reaction steps within the zeolite microenvironment (ACS Catal., 2018;ACS Catal., 2019;ACS Catal., 2020;Nat. Commun., 2021).Based on this body of work, this review article reveals the dynamic transition of active sites in the MTH catalytic process over zeolites, shifting from the traditionally recognized Brønsted acid sites (BAS) to dynamic changes in organic-inorganic hybrid supramolecular (OIHS) composite active sites. It also illustrates the dynamic evolution of reaction intermediates, progressing from surface methoxy species (SMS) to active ion pairs complex (AIPC), and further to inert complexes (IC), leading to the transformation of the reaction mechanism from the initial direct C-C coupling mechanism to an efficient hydrocarbon pool (HCP) autocatalytic mechanism.Furthermore, the catalytic cycles shift from BAS-acid catalysis to multistage catalytic reaction cycles operating synergistically, constructing a catalytic reaction hypercycle network. This transition guides the reaction process from autocatalytic initiation to autocatalytic maintenance and ultimately to autocatalytic termination.These insights emphasize the complexity of the catalytic mechanism in zeolite-catalyzed MTH reactions, especially the catalytic essence of zeolites under realistic conditions, which is often dynamicrather than confined to simplified active sites and the static BAS catalysis traditionally perceived.

This work, titled "Dynamic Catalytic Mechanism of the Methanol-to-Hydrocarbons Reaction over Zeolites," was published in Accountsof Chemical Research. Thiswork was supported by the Strategic Priority Research Program of CAS, the National Natural Science Foundation of China, the National Key R&D Program of China, and the Youth Innovation Promotion Association of CAS. (Textby WuXinqiang)

Dynamic Catalytic Mechanism of the Methanol-to-Hydrocarbons Reaction over Zeolites, Xinqiang Wu，Yingxu Wei^*，Zhongmin，Liu^*. 56(14):2001-2014,2023.