Strong Stabilization of Co Nanoparticles by CeO <sub>2‐x</sub> Clusters in Inverse CeO <sub>x</sub> /Co Catalysts for Enhanced CO <sub>2</sub> Methanation
Yu Gao, Valery Muravev, Yonghui Fan, Hao Zhang, Jorden Wagemakers, Alexander Parastaev, Nikolay Kosinov, Emiel J. M. Hensen
Abstract
Abstract Inverse catalysts, where metal oxide species are dispersed over metallic nanoparticles, represent a promising class of materials for accelerating various chemical reactions. However, stabilizing metal nanoparticles with a small amount of oxide clusters remains a significant challenge, as the metallic phase tends to sinter under reaction conditions due to insufficient immobilization. In this study, flame spray pyrolysis is employed to synthesize uniformly sized inverse CeO x /Co catalysts for CO 2 methanation (Sabatier reaction). It is found that small, highly reducible CeO 2‐x clusters effectively stabilize metallic cobalt nanoparticles, thereby preventing sintering even during hydrogen reduction at 500 °C and during CO 2 hydrogenation. Detailed operando characterization demonstrates that this stabilization leads to a high density of metallic Co sites interfaced with CeO 2‐x clusters, which facilitates CO 2 activation into carbonyl (CO * ) intermediates, resulting in significantly enhanced CH 4 formation rates. Notably, an inverse CeO x /Co catalyst containing 20 mol% Ce exhibits a methanation rate an order of magnitude higher than that of a CeO 2 ‐free Co catalyst. These findings highlight the dual role of CeO 2‐x clusters in both stabilizing Co nanoparticles and enhancing catalytic performance, offering a robust strategy for improving CO 2 hydrogenation performance.