Gallium: A Universal Promoter Switching CO <sub>2</sub> Methanation Catalysts to Produce Methanol
Wei Zhou, Colin Hansen, Weicheng Cao, Enzo Brack, Scott R. Docherty, Christian Ehinger, Yuhao Wang, Chunliang Wang, Christophe Copéret
Abstract
High Resolution Image Download MS PowerPoint Slide Hydrogenation of CO 2 to methanol is foreseen as a key step to close the carbon cycle. In this study, we show that introducing Ga into silica-supported nanoparticles based on group 8–9 transition noble metals (M = Ru, Os, Rh, and Ir – M Ga@SiO 2 ) switches their reactivity from producing mostly methane (sel. > 97%) to producing methanol (>50% CH 3 OH/DME sel.) alongside CO as the only byproduct. These silica-supported catalysts, prepared via a surface organometallic chemistry (SOMC) approach, consist of small, alloyed, and narrowly distributed M Ga nanoparticles, as evidenced by X-ray absorption spectroscopy (XAS) and CO adsorption studies. Notably, detailed in situ XAS and diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) studies complemented with density functional theory (DFT) calculations indicate that Ga generates stable bulk M Ga alloys. The bulk M Ga alloys persist during CO 2 hydrogenation according to XAS, resulting in suppressed methanation. Meanwhile, a small fraction of surface GaO x and thereby M Ga–GaO x interfaces are formed, as evidenced by IR spectroscopy, likely responsible for stabilizing methoxy intermediates and favoring methanol formation.