Journal of Catalysis, Vol.394, 397-405, 2021
Mechanochemical in-situ incorporation of Ni on MgO/MgH2 surface for the selective O-/C-terminal catalytic hydrogenation of CO2 to CH4
The conversion of CO2 to CH4 has great significance to energy supply and environment protection. For the first time, we report a Ni-incorporated MgO/MgH2 material synthesized via a facile mechanochemical ball-milling method for thermo-catalytic CO2 methanation. The Ni-incorporated MgO/MgH2 material achieves the hydrogenation of CO2 to CH4 with a space-time yield (STY) of 944.6 g kg(-1) h(-1) and a selectively of 99.5% at 300 degrees C under 1.0 MPa H-2/CO2/N-2, which are comparable to traditional catalysts and much better than Ni/MgO or Ni/MgH2 mixtures. This facile mechanochemical ball milling can in-situ incorporate Ni to MgO surface generating a stable "Mg-Ni-O" structure, which can promote the activation of H-2 and CO2 molecules. DFT calculations suggest that Ni-incorporated MgO(1 10) can offer electropositive H+ (1s(0)) for the O-terminal hydrogenation of CO2 to CO* species, while the following C-terminal hydrogenation to CH4 is performed on MgH2 (001) with electronegative H (1s(2)) as hydrogen source. This selective hydrogenation via specific hydrogen species on Ni-incorporated MgO/MgH2 can inspire catalysts design for the conversion of CO2 to value-added chemicals. (C) 2020 Elsevier Inc. All rights reserved.