SCI和EI收录∣中国化工学会会刊

›› 2017, Vol. 25 ›› Issue (10): 1442-1448.DOI: 10.1016/j.cjche.2017.03.024

• Catalysis, Kinetics and Reaction Engineering • 上一篇    下一篇

Effect of the Ni size on CH4/CO2 reforming over Ni/MgO catalyst:A DFT study

Yunpeng Guo1,2, Jie Feng1,2, Wenying Li1,2   

  1. 1 Key Laboratory of Coal Science and Technology for Ministry of Education and Shanxi Province(Taiyuan University of Technology), Taiyuan 030024, China;
    2 Training Base of State Key Laboratory of Coal Science and Technology Jointly Constructed by Shanxi Province and Ministry of Science and Technology, Taiyuan University of Technology, Taiyuan 030024, China
  • 收稿日期:2016-12-31 修回日期:2017-03-17 出版日期:2017-10-28 发布日期:2017-03-28
  • 通讯作者: Wenying Li,E-mail address:ying@tyut.edu.cn
  • 基金资助:
    Supported by the National Natural Science Foundation of China (U1361202, 51276120).

Effect of the Ni size on CH4/CO2 reforming over Ni/MgO catalyst:A DFT study

Yunpeng Guo1,2, Jie Feng1,2, Wenying Li1,2   

  1. 1 Key Laboratory of Coal Science and Technology for Ministry of Education and Shanxi Province(Taiyuan University of Technology), Taiyuan 030024, China;
    2 Training Base of State Key Laboratory of Coal Science and Technology Jointly Constructed by Shanxi Province and Ministry of Science and Technology, Taiyuan University of Technology, Taiyuan 030024, China
  • Received:2016-12-31 Revised:2017-03-17 Online:2017-10-28 Published:2017-03-28
  • Supported by:
    Supported by the National Natural Science Foundation of China (U1361202, 51276120).

摘要: Carbon deposition is sensitive to the metal particle sizes of supported Ni catalysts in CH4/CO2 reforming. To explore the reason of this phenomenon, Ni4, Ni8, and Ni12 which reflect the different cluster thicknesses supported on the MgO(100) slabs, have been employed to simulate Ni/MgO catalysts, and the reaction pathways of CH4/CO2 reforming on Nix/MgO(100) models are investigated by density functional theory. The reforming mechanisms of CH4/CO2 on different Nix/MgO(100) indicate the energy barriers of CH4 dissociated adsorption, CH dissociation, and C oxidation three factors are all declining with the decrease of the Ni cluster sizes. The Hirshfeld charges analyses of three steps as described above show only Ni atoms in bottom two layers can obtain electrons from the MgO supporters, and the main electron transfer occurs between adsorbed species and their directly contacted Ni atoms. Due to more electron-rich Ni atoms in contact with the MgO supporters, the Ni/MgO catalysts with small Ni particles have a strong metal particle size effect and lead to its better catalytic activity.

关键词: Particle size effect, Ni/MgO catalyst, CH4/CO2 reforming, Density functional theory

Abstract: Carbon deposition is sensitive to the metal particle sizes of supported Ni catalysts in CH4/CO2 reforming. To explore the reason of this phenomenon, Ni4, Ni8, and Ni12 which reflect the different cluster thicknesses supported on the MgO(100) slabs, have been employed to simulate Ni/MgO catalysts, and the reaction pathways of CH4/CO2 reforming on Nix/MgO(100) models are investigated by density functional theory. The reforming mechanisms of CH4/CO2 on different Nix/MgO(100) indicate the energy barriers of CH4 dissociated adsorption, CH dissociation, and C oxidation three factors are all declining with the decrease of the Ni cluster sizes. The Hirshfeld charges analyses of three steps as described above show only Ni atoms in bottom two layers can obtain electrons from the MgO supporters, and the main electron transfer occurs between adsorbed species and their directly contacted Ni atoms. Due to more electron-rich Ni atoms in contact with the MgO supporters, the Ni/MgO catalysts with small Ni particles have a strong metal particle size effect and lead to its better catalytic activity.

Key words: Particle size effect, Ni/MgO catalyst, CH4/CO2 reforming, Density functional theory