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

Au/Mg(OH) catalysts have been reported to be far more active in the catalytic low-temperature CO oxidation (below 0 °C) than the thoroughly investigated Au/TiO catalysts. Based on kinetic and in situ infrared spectroscopy (DRIFTS) measurements, we demonstrate that the comparatively weak interaction of Au/Mg(OH) with CO 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/TiO also catalyzes CO formation, but does not allow for CO desorption, which results in self-poisoning. At higher temperatures (above 0 °C), however, CO formation is rate-limiting, which results in a much higher activity for Au/TiO under these reaction conditions.