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

Angewandte Chemie - International Edition

5 years ago

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

Ferdi Schüth, Felix Lehnert, Daniel Widmann, Yuchen Wang, R. Jürgen Behm, Dong Gu

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 (<0 °C). Owing to the weak interaction of CO2 with Au/Mg(OH)2, which enables product desorption, this catalyst is far more active than other Au catalysts for the continuous CO oxidation below 0 °C.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/anie.201702178