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.

Automated summary

The study presents a Ni-incorporated MgO/MgH2 material synthesized via a facile mechanochemical ball-milling method for thermo-catalytic CO2 methanation. The material achieves high catalytic performance in converting CO2 to CH4 with superior selectivity at low temperature. This selective hydrogenation process can potentially inspire the design of catalysts for the conversion of CO2 to value-added chemicals.