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要旨

Metal-support interactions, which are essential for the design of supported metal catalysts, used, e.g., for CO₂ activation, are still only partially understood. In this study of gold-loaded In₂O₃ and CeO₂ catalysts during CO₂ hydrogenation using near-ambient pressure X-ray photoelectron spectroscopy, supported by near edge X-ray absorption fine structure, we demonstrate that the role of the noble metal strongly depends upon the choice of the support material. Temperature-dependent analyses of X-ray photoelectron spectra under reaction conditions reveal that gold is reduced on CeO₂, enabling direct H₂ activation, but oxidized on In₂O₃, leading to decreased activity of Au/In₂O₃ compared to bare In₂O₃. At elevated temperatures, the catalytic activity of the In₂O₃ catalysts strongly increases as a result of facilitated CO₂ and (In₂O₃-based) H₂ activation, while the catalytic activity of Au/CeO₂ is limited by reoxidation by CO₂. Our results underline the importance of operando studies for understanding metal-support interactions to enable a rational support selection in the future.