文献类型：期刊文献

英文题名：Ketene Conversion Chemistry within Mordenite Zeolite: Pore-Size-Dependent Reaction Mechanism, Product Selectivity, and Catalytic Activity

作者：Xiong, Danfeng[1,2];Lai, Zhuangzhuang[1,2];Chen, Jianfu[1,2];Yuan, Haiyang[1,2,3];Wang, Haifeng[1,2]

机构：[1]East China Univ Sci & Technol, Ctr Computat Chem, State Key Lab Green Chem Engn & Ind Catalysis, Shanghai 200237, Peoples R China;[2]East China Univ Sci & Technol, Res Inst Ind Catalysis, Shanghai 200237, Peoples R China;[3]East China Univ Sci & Technol, Shanghai Engn Res Ctr Hierarch Nanomat, Sch Mat Sci & Engn, Key Lab Ultrafine Mat,Minist Educ, Shanghai 200237, Peoples R China

年份：2025

卷号：147

期号：20

起止页码：17303

外文期刊名：JOURNAL OF THE AMERICAN CHEMICAL SOCIETY

收录：;EI(收录号：20252018408043);WOS:【SCI-EXPANDED(收录号:WOS:001485870400001)】；

基金：This project was supported by the National Key R&D Program of China (2021YFA1500700), NSFC (22203031, 91945302, 92045303, and 22473043), and the Fundamental Research Funds for the Central Universities.

语种：英文

外文关键词：Catalysis - Free energy - Reaction intermediates

摘要：The oxide-zeolite bifunctional catalyst for ketene-bridged syngas conversion has gained great attention for addressing the selectivity challenge in light olefin production, where zeolite dominates the ketene conversion selectivity. However, the atomic-level mechanism underlying ketene-to-light olefin conversion within zeolite remains unclear. Herein, we focus on mordenite (MOR) zeolite and perform systematic first-principles calculations combined with microkinetic simulations to elucidate pore-type-dependent reaction networks for ketene-to-light olefin conversion. Our microkinetic results reveal that ketene conversion within MOR follows an autocatalytic process initiated by the Br & oslash;nsted acid site, involving the generation and subsequent catalysis of reactive intermediates. Time-dependent dynamic evolution simulation shows that within the 12-membered-ring (12MR) pore, a thermodynamically stable five-membered-ring carbocation (FMR-CH3 +) self-evolves and acts as the active center to convert CH2CO to multihydrocarbons. Instead, in the 8-membered-ring side pocket (8MR), direct CH3 + formation occurs via acetyl carbocation (CH3CO+) decarbonylation, inducing CH2CO conversion with exclusive ethylene selectivity. The distinct reaction mechanisms and product selectivities are attributed to the thermodynamic and kinetic constraints of cyclic/long-chain intermediate formation imposed by the smaller 8MR pore. Despite its higher free energy barrier, 8MR is identified as the key active site for light olefin formation due to its lower dependence on ketene pressure. We also highlight the critical factors influencing both the selectivity and activity of light olefin formation, offering valuable insights for the optimization of MOR catalysts. This study provides a quantitative mechanistic understanding of ketene conversion, emphasizing the role of pore structure in shaping catalytic activity and product selectivity, which may facilitate the design of efficient zeolite-based catalysts.