Gao Shushu, Ye Fangxiu, Xu Shutao, Wei Yingxu, Liu Zhongmin
National Engineering Research Center of Lower-Carbon Catalysis Technology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Sinopec Beijing Research Institute of Chemical Industry, Beijing 100013, China.
Chem Commun (Camb). 2025 Feb 25;61(18):3636-3648. doi: 10.1039/d4cc06574c.
The methanol-to-olefins (MTO) process, driven by zeolites or molecular sieves, a cornerstone of C1 chemistry, has established a substantial pathway for generating olefin products from non-petroleum sources. Molecular sieves exhibit significant benefits in catalysis with shape selectivity due to the unique confinement environment and acidic properties, featuring their molecular sieving and confinement effects. Significantly, eight-membered ring (8-MR) and cavity-type molecular sieve catalysts, characterized by large cage volumes and restricted window openings, exhibit distinctive host-guest interactions between the cavity structure and the reactants, intermediates, and products within the confined space, thereby revealing the cavity-controlled methanol conversion principle in molecular adsorption and diffusion, intermediate formation, reaction pathway, and catalyst deactivation processes. This review mainly summarizes molecular adsorption characteristics and diffusion behavior, as well as the mechanisms of the MTO reaction and catalyst deactivation within cavity-type molecular sieves. A comprehensive introduction is provided on the variations in preferential adsorption sites and diffusion behavior of guest molecules induced by different cavity structures within cavity-type molecular sieves. Furthermore, the critical intermediate generation governed by cavity structure and the nonuniform distribution of coke species within the catalyst were also discussed. The cavity-controlled catalytic principle of the MTO reaction driven by 8-MR and cavity-type molecular sieves provides valuable insights for the modification of molecular sieve catalysts and the optimization of the MTO process and also promotes broader application of these catalysts in other C1 chemical reactions.
由沸石或分子筛驱动的甲醇制烯烃（MTO）工艺是C1化学的基石，为从非石油来源生产烯烃产品开辟了一条重要途径。由于独特的受限环境和酸性特性，分子筛在催化过程中表现出显著的形状选择性优势，具有分子筛和限域效应。值得注意的是，具有大笼体积和受限窗口开口的八元环（8-MR）和笼型分子筛催化剂，在受限空间内的笼结构与反应物、中间体和产物之间表现出独特的主客体相互作用，从而揭示了分子吸附和扩散、中间体形成、反应途径以及催化剂失活过程中的笼控甲醇转化原理。本综述主要总结了笼型分子筛内的分子吸附特性和扩散行为，以及MTO反应和催化剂失活的机理。全面介绍了笼型分子筛内不同笼结构引起的客体分子优先吸附位点和扩散行为的变化。此外，还讨论了由笼结构控制的关键中间体生成以及催化剂内焦炭物种的不均匀分布。由8-MR和笼型分子筛驱动的MTO反应的笼控催化原理为分子筛催化剂的改性和MTO工艺的优化提供了有价值的见解，也促进了这些催化剂在其他C1化学反应中的更广泛应用。
