催化学报 ›› 2025, Vol. 72: 289-300.DOI: 10.1016/S1872-2067(24)60278-0

• 论文 • 上一篇    下一篇

K对Hägg碳化物逆水煤气变换反应作用的理论研究

任宪轩a, Rozemarijn D. E. Krösschella, 门卓武b, 王鹏a,b,*(), Ivo A. W. Filota,*(), Emiel J. M. Hensena,*()   

  1. a埃因霍温理工大学化学与化学工程系, 无机材料与催化实验室, 埃因霍温, 荷兰
    b北京低碳清洁能源研究院, 北京 102211, 中国
  • 收稿日期:2024-12-05 接受日期:2025-02-03 出版日期:2025-05-18 发布日期:2025-05-20
  • 通讯作者: *电子信箱: p.wang@tue.nl (王鹏),i.a.w.filot@tue.nl (I. Filot),e.j.m.hensen@tue.nl (E. Hensen).

A theoretical study of the role of K on the reverse water-gas shift reaction on Hägg carbide

Xianxuan Rena, Rozemarijn D. E. Krösschella, Zhuowu Menb, Peng Wanga,b,*(), Ivo A. W. Filota,*(), Emiel J. M. Hensena,*()   

  1. aLaboratory of Inorganic Materials and Catalysis, Department of Chemistry and Chemical Engineering, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
    bNational Institute of Clean-and-Low-Carbon Energy, Future Science and Technology City, Beijing 102211, China
  • Received:2024-12-05 Accepted:2025-02-03 Online:2025-05-18 Published:2025-05-20
  • Contact: *E-mail: p.wang@tue.nl (P. Wang), i.a.w.filot@tue.nl (I. Filot), e.j.m.hensen@tue.nl (E. Hensen).

摘要: 钾(K)作为助剂可以提高铁基催化剂在逆水煤气变换(rWGS)反应中的催化性能, 这一特性与CO2-H2混合物的费托(FT)合成过程密切相关. 为了阐明K助剂的作用机理, 我们结合密度泛函理论(DFT)计算和微观动力学建模, 对Hägg碳化物(χ-Fe5C2)的两个代表性表面终端, 即(010)和(510)进行了研究. 结果表明, K2O的存在增强了CO2和H2在Hägg碳化物上的吸附能力, 并通过提高靠近助剂氧化物的Fe原子的电子密度来促进吸附CO2的C-O键解离. 此外, 表面Fe原子电子密度的的增加导致了与吸附CO2的键合轨道的电子排斥效应增强. 微观动力学模拟预测, K2O在CO2-FT合成过程中提高了CO2转化率. K2O还增强了CO的吸附和解离, 促进了甲烷的形成, 甲烷在这里被用作CO2-FT合成过程中碳氢化合物形成的典型代表. 在CO2-FT反应体系中, CO解离和通过H2O去除O作为速率控制步骤相互竞争.

关键词: 费托合成, H?gg碳化铁, 逆水煤气变换, 钾, 密度泛函理论

Abstract:

Potassium (K) is known to enhance the catalytic performance of Fe-based catalysts in the reverse water-gas shift (rWGS) reaction, which is highly relevant during Fischer-Tropsch (FT) synthesis of CO2-H2 mixtures. To elucidate the mechanistic role of K promoter, we employed density functional theory (DFT) calculations in conjunction with microkinetic modelling for two representative surface terminations of Hägg carbide (χ-Fe5C2), i.e., (010) and (510). K2O results in stronger adsorption of CO2 and H2 on Hägg carbide and promotes C-O bond dissociation of adsorbed CO2 by increasing the electron density on Fe atoms close to the promoter oxide. The increased electron density of the surface Fe atoms results in an increased electron-electron repulsion with bonding orbitals of adsorbed CO2. Microkinetics simulations predict that K2O increases the CO2 conversion during CO2-FT synthesis. K2O also enhances CO adsorption and dissociation, facilitating the formation of methane, used here as a proxy for hydrocarbons formation during CO2-FT synthesis. CO dissociation and O removal via H2O compete as the rate-controlling steps in CO2-FT.

Key words: Fischer-Tropsch synthesis, H?gg carbide, Reverse water-gas shift, Potassium, Density functional theory