Chinese Journal of Catalysis ›› 2026, Vol. 87: 113-125.DOI: 10.1016/S1872-2067(26)65095-4

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The smallest Ni species triggering selective hydrogenation of CO2 to methane: Ni dimer embedded in MFI and enhancement of MnOx

Sen Wanga,1, Shiying Lia,1, Rui Genga,b, Bo Zhouc,*(), Pengfei Wanga, Zhangfeng Qina, Mei Donga, Jianguo Wanga,b, Unni Olsbyed, Weibin Fana,*()   

  1. a State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, Shanxi, China
    b University of the Chinese Academy of Sciences, Beijing 100049, China
    c Chemistry and Chemical Engineering Guangdong Laboratory, Shantou 515031, Guangdong, China
    d Department of Chemistry, Centre for Materials and Nanoscience (SMN), University of Oslo, P.O. Box 1033, Blindern, NO-0315 Oslo, Norway
  • Received:2025-12-03 Accepted:2026-01-13 Online:2026-08-18 Published:2026-06-24
  • About author:1Contributed equally to this work.
  • Supported by:
    National Key R&D Program of China(2023YFB4103102);National Natural Science Foundation of China(21991090);National Natural Science Foundation of China(21991092);National Natural Science Foundation of China(22322208);National Natural Science Foundation of China(22272195);National Natural Science Foundation of China(U22A20431);National Natural Science Foundation of China(22402071);Fundamental Research Program of Shanxi Province(202203021224009);Fundamental Research Program of Shanxi Province(202403021212302);Innovation foundation of Institute of Coal Chemistry, Chinese Academy of Sciences(SCJC-DT-2023-06);Youth Innovation Promotion Association of Chinese Academy of Sciences (CAS)(2021172)

Abstract:

Ni-based catalysts have shown significant potential in CO2 methanation, but the high catalytic performance is usually obtained at quite high Ni loading, as small particles just transform CO2 into CO via reverse water gas shift reaction. Thus, a scientifically and practically important work is clarification of the structure of the smallest active Ni species and the catalytic activity of structurally different Ni species. Here, MnOx-modulated metallic nickel dimers (MnOx-Ni2) were embedded in silicalite-1 framework at a Ni loading of ~0.86%. It’s CO2 conversion, CH4 selectivity and CH4 space time yield (STY) surprisingly reach ~76%, ~98% and ~450 mol·molNi-1·h-1 at 400 °C, 0.5 MPa and 12000 mL·g-1·h-1. Such a catalytic performance can be well maintained at least within 200 h. In-situ spectroscopy, density functional theory (DFT) calculation and ab initio molecular dynamics simulation results confirm that Ni dimer (Ni2) is the smallest Ni cluster triggering the CO2 methanation and the CH4 formation activity is linearly increased with the Ni2 content. Introduction of MnOx not only increases the number of Ni2 species, but also improves its intrinsic activity in CO2 methanation, as MnOx enhances the electronic density of Ni species and facilitates NiO reduction to MnOx-Ni2 species. This species shows higher H2 dissociation activity than single atom Ni (Ni1), pure Ni2 and large Ni nanoparticles (NPs). In addition, it exhibits much stronger CO adsorption and lower energy barrier of CO* intermediate hydrogenation to CH4. In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), isotope-labeled in-situ DRIFTS, on line mass spectroscopy (MS), Proton transfer reaction time of flight PTR TOF-MS and DFT calculation results reveal that CO2 hydrogenation to methane on MnOx-Ni2@MFI mainly follows the HCOO* and CO* intermediates route.

Key words: Zeolite, Confined encapsulation, Ni-based catalyst, Nickel dimers, CO2 hydrogenation, Reaction mechanism