Efficient CO2 hydrogenation over mono- and bi-metallic RuNi/MCM-41 catalysts: Controlling CH4 and CO products distribution through the preparation method and/or partial replacement of Ni by Ru

[Display omitted] •CO2 hydrogenation products distribution strongly depends on Ni − MCM-41 preparation.•One-pot synthesis of Ni − MCM-41 promotes RWGS shifting reaction to syngas production.•Ni dispersion on MCM-41via impregnation promotes CO2 methanation (CH4 production)•Addition of Ru on Ni/MCM-41 causes redispersion of Ni particles favoring methanation.•No metal-to-metal synergy toward methanation on RuNi/MCM-41; Ru/MCM-41 is superior. CO2 methanation is receiving special attention nowadays due to the urgent environmental and energy need to control/recycle CO2 emissions. Herein the reaction is investigated over mono- and bi-metallic RuNi catalysts supported on mesoporous MCM-41 materials. Monometallic-Ru catalysts were always superior to their monometallic-Ni counterparts, while the bimetallic-RuNi, although outperforming monometallic-Ni, were inferior to monometallic-Ru. The CO2 methanation efficiency of monometallic-Ni catalysts was found to be highly dependent on the catalyst preparation method: One-pot synthesis provided catalysts almost completely ineffective for methanation, but very effective for the reverse-water–gas-shift (RWGS) reaction producing syngas at low temperatures. In striking contrast, compositionally identical Ni catalysts prepared by impregnation were efficient in CO2 methanation. An important for practical purposes redispersion of already stabilized large Ni crystallites was achieved by adding small amounts of Ru via the formation of core(Ru)-shell(Ni) nano-configurations. Detailed characterizations, kinetic and in-situ DRIFTS studies allowed the convincing interpretation of the novel findings.