The catalytic efficiency of Fe-containing nanocomposites based on highly dispersed silica in the reaction of CO 2 hydrogenation

Oxide Ni(80)Fe(20)/SiO 2 , Co(93)Fe(7)/SiO 2 , and Ni(19)Co(77)Fe(4)/SiO 2 nanocomposites (NCs) were prepared using highly dispersed silica. It was modified by solvate-stimulated adsorption of a mixture of respective metal salts with subsequent thermal decomposition of adsorbates. Hydrogen reduction of the embedded metal oxides produces metallic Ni and Co nanoparticles (NPs) that showed high efficiency in catalytic CO 2 hydrogenation to methane. The prepared silica-based NCs with embedded metal oxides and metallic Ni or Co NPs were studied by nitrogen adsorption, PXRD, and SEM–EDS methods. The metal oxide modifiers increase the contribution of mesopores to the total porosity of the resulting NCs, reducing that of macropores. The metal oxides reduction to the metallic state has a minor effect on the texture parameters. The content-dominant metal forms the nanoscale crystallites on the support surface during the reduction of metal oxides and the preparation of the NC catalysts. In the terms of methane yield at 350 °C, the studied NC catalysts can be arranged as follows NiFe/SiO 2 (77%) > CoFe/SiO 2 (74%) > NiCoFe/SiO 2 (72%). Iron additives can improve the hydrogenation efficiency in the binary NiFe and CoFe compositions but cause no positive effect within the ternary NiCoFe composition. TPD MS studies demonstrate that the catalytic methanation reaction can pass by the mechanism accounting for the formation of oxygen-containing intermediates.