Gallium Switches the Selectivity of Classical Methanation Catalysts to Produce Methanol from CO2

The development of efficient catalysts for the hydrogenation of CO2 to methanol is foreseen as a key step to close the carbon cycle and enable sustainable development. In this study, we show that introducing Ga into silica-supported nanoparticles based on group 8-9 noble transition metals (M = Ru, Os, Rh, and Ir – MGa@SiO2), switches their reactivity from producing purely CH4 (selectivity >97%) to producing methanol (50% for CH3OH/DME) alongside CO as the only byproduct. These silica-supported catalysts, prepared via a surface organometallic chemistry (SOMC) approach, contain small, narrowly distributed MGa alloyed nanoparticles, evidenced by X-Ray absorption spectroscopy and CO adsorption studies. Notably, under CO2 hydrogenation conditions, detailed in-situ XAS and DRIFTS studies complemented with density functional theory (DFT) calculations indicate that Ga generates stable MGa alloys, which persist during CO2 hydrogenation and favor the formation of methoxy species, driving the overall reaction to methanol formation while suppressing methanation.