文献类型：期刊文献

英文题名：Mechanistic insights into electronic modulation of binuclear iron-based zeolites for selective oxidation of methane to methanol

作者：Cheng, Lu[1,2];Cao, Xiao-Ming[1,2,3]

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]Shanghai Jiao Tong Univ, Sch Chem & Chem Engn, State Key Lab Synergist Chem Bio Synth, Shanghai 200240, Peoples R China

年份：2025

卷号：27

期号：30

起止页码：16113

外文期刊名：PHYSICAL CHEMISTRY CHEMICAL PHYSICS

收录：;EI(收录号：20252918812043);WOS:【SCI-EXPANDED(收录号:WOS:001529195500001)】；

基金：This work was financially supported by the National Key Research and Development Program of China (2023YFA1507601) and National Natural Science Foundation of China (22022302, 92045303, and 91845111).

语种：英文

外文关键词：Atoms - Catalyst activity - Chemical activation - Density functional theory - Hydrogen - Hydrogen bonds - Iron - Iron compounds - Methane - Methanol - Oxidation - Oxygen - Thermodynamics

摘要：Conceptually, direct methane-to-methanol (DMTM) conversion represents an efficient approach for methane (CH4) valorization, which is thermodynamically feasible at ambient temperature. However, this process consistently faces a conversion-selectivity trade-off. Particularly, when employing dioxygen (O2) as the oxidizing agent, an additional compromise arises between O2 activation and the generation of reactive oxygen species necessary for CH4 activation. Enzyme-like iron-based zeolites are regarded as promising catalysts for DMTM. We investigated possible iron clusters in ZSM-5 based on ab initio thermodynamics analysis and identified the binuclear [Fe-(mu-O)2-Fe]2+ site anchored by Al pairs as the most stable configuration in the Fe/ZSM-5 catalyst under the preparation conditions reported preparation conditions. Density functional theory calculations revealed a Mars-van-Krevelen-like (MvK-like) mechanism for DMTM over the binuclear iron sites, offering a pathway to circumvent the challenge of simultaneously activating CH4 and O2, thereby enhancing catalyst activity. Nevertheless, the activity of this Fe/ZSM-5 catalyst remains constrained by surface oxygen species reactivity. Moreover, the [Fe-(mu-O)2-Fe]2+ site exhibits marginal preference for methanol O-H bond scission over methane C-H bond scission, compromising the intrinsic limitation between methane conversion and methanol overoxidation. The introduction of a second metal component could electronically regulate surface oxygen reactivity, effectively tuning DMTM performance. While the fundamental trade-off between O2 activation and methane conversion persists, methane C-H bond scission over [Fe-(O2)(mu-O)2-M]2+ was always found to be the rate-determining step for Fe-based binuclear catalysts. Based on the ligand-to-metal charge transfer (LMCT)-enabled hydrogen atom transfer (HAT) mechanism for the methane C-H bond, we propose the third ionization energy (IE3) of the secondary metal component as an effective descriptor for predicting methane conversion efficiency over these Fe-based binuclear catalysts. Remarkably, the elevated IE3 of Zn due to the fully occupied d orbital of Zn2+ renders the hetero-binuclear Fe-Zn/ZSM-5 with the [Fe-(mu-O)2-Zn]2+ site to be a promising catalyst for enhancing methane conversion. Furthermore, the high IE3 of Zn suppresses methanol O-H bond scission, thereby improving methanol selectivity. These mechanistic insights provide a guide for the rational design of DMTM catalysts through the electronic synergy engineering of hetero-binuclear metal centers.