Avoiding Self‐Poisoning: A Key Feature for the High Activity of Au/Mg(OH)2 Catalysts in Continuous Low‐Temperature CO Oxidation

Au/Mg(OH)2 catalysts have been reported to be far more active in the catalytic low‐temperature CO oxidation (below 0 °C) than the thoroughly investigated Au/TiO2 catalysts. Based on kinetic and in situ infrared spectroscopy (DRIFTS) measurements, we demonstrate that the comparatively weak interaction of Au/Mg(OH)2 with CO2 formed during the low‐temperature reaction is the main reason for the superior catalyst performance. This feature enables rapid product desorption and hence continuous CO oxidation at temperatures well below 0 °C. At these temperatures, Au/TiO2 also catalyzes CO2 formation, but does not allow for CO2 desorption, which results in self‐poisoning. At higher temperatures (above 0 °C), however, CO2 formation is rate‐limiting, which results in a much higher activity for Au/TiO2 under these reaction conditions. Kinetic and in situ IR measurements show that the interaction of the catalyst surface with the CO2 formed during low‐temperature CO oxidation is the crucial support effect at low temperatures (