University of Science and Technology Liaoning School of Civil Engineering
University of Science and Technology Liaoning School of Chemical Engineering

基于密度泛函理论和经典过渡态理论，探究了石墨炭负载单原子Fe催化剂（Fe/G）异相还原NO的微观机理，并对催化剂失活原因进行分析。结果表明，基于E-R机理，NO还原反应依次经历了N2O形成与释放、N2形成与释放四个阶段。而基于L-H机理，NO还原反应主要经历了N2形成与释放两个阶段。在E-R机理作用下，NO分子以N,O-down结构吸附在Fe原子上发生的NO还原反应的控速步骤能垒值仅为15.5 kJ/mol，小于其余路径控速步骤能垒值。由能垒角度分析，Fe原子上残留的活性氧被还原的能垒值高于NO还原生成N2的能垒值。NO分解后残留在Fe原子表面的活性氧抑制了NO的吸附与还原，Fe原子活性位的缺失导致催化剂的失活，单原子Fe的存在促进了NO还原反应的进行。由动力学角度分析，随着反应温度的升高，NO还原速率较活性氧转移速率提升更为显著。

The mechanism of nitrogen oxide (NO) reduction over graphite carbon-supported single-atom iron (Fe) catalyst (Fe/G) was investigated by density functional theory (DFT) and transition state theory (TST). The catalyst deactivation was also analyzed. The results revealed that the NO reduction, based on the Eley-Rideal (E-R) mechanism, underwent four stages including N2O formation and release as well as N2 formation and release. However, the NO reduction only involved two stages according to Langmuir-Hinshelwood (L-H) mechanism: N2 formation and release. Furthermore, for the E-R mechanism, the rate-controlling step was NO reduction, where a NO molecule was adsorbed on an Fe atom with an N, O-down structure with energy barrier of 15.5 kJ/mol, lower than that of other paths. Energy barrier analysis indicated that the energy barrier for the reduction of reactive oxygen species was higher than that for the formation of N2. Reactive oxygen species remaining on the surface of Fe atoms after NO decomposition inhibited the adsorption and reduction of NO, leading to catalyst deactivation due to the absence of active sites. The single-atom Fe species promoted the NO reduction. Kinetic analysis results suggested that, upon increasing the reaction temperature, the NO reduction rate increased more significantly than the reactive oxygen transfer rate.

辽宁省教育厅青年项目(JYTQN2023237)资助

赵妍, 李响, 黄金凯, 李先春, 朱亚明, 王焕然. 石墨炭负载单原子铁催化剂非均相还原 NO 的微观作用机理：DFT研究[J]. 燃料化学学报（中英文）, 2024, 52(5): 717-724.

ZHAO Yan, LI Xiang, HUANG Jinkai, LI Xianchun, ZHU Yaming, WANG Huanran. Mechanism of heterogeneous reduction of NO over graphite-supported single-atom Fe catalyst: DFT study[J]. Journal of Fuel Chemistry and Technology, 2024, 52(5): 717-724.