Fundamental Aspects of Ceria Supported Au Catalysts Probed by In Situ/Operando Spectroscopy and TAP Reactor Studies

Abstract

The discovery of the activity of dispersed gold nanoparticles three decades ago paved the way for a new era in catalysis. The unusual behavior of these catalysts sparked many questions about their working mechanism. In particular, Au/CeO2 proved to be an efficient catalyst in several reactions such as CO oxidation, water gas shift, and CO2 reduction. Here, by employing findings from operando X‐ray absorption spectroscopy at the near and extended Au and Ce LIII energy edges, we focus on the fundamental aspects of highly active Au/CeO2 catalysts, mainly in the CO oxidation for understanding their complex structure‐reactivity relationship. These results were combined with findings from in situ diffuse reflectance FTIR and Raman spectroscopy, highlighting the changes of adlayer and ceria defects. For a comprehensive understanding, the spectroscopic findings will be supplemented by results of the dynamics of O2 activation obtained from Temporal Analysis of Products (TAP). Merging these results illuminates the complex relationship among the oxidation state, size of the Au nanoparticles, the redox properties of CeO2 support, and the dynamics of O2 activation.

Photocatalytic Easy Recovery of Orthophosphates Contaminants in Water Using Amberlite‐732 Cationic‐Resin Exchanged by Ce3+and Ce3+‐Au3+ Species

“…Indeed, Au particles (seen by SEM) were only a part of total gold stored, it can be assumed that some metallic gold isolated cations or clusters have penetrated (by inclusion) inside Amberlite-732 before the thermal treatment; while, after the heat treatment, some Au 0 particles have probably nucleated at the surface of these two Ce-Au catalysts. This last result is in good agreement with the work of Abdel-Magged et al [38]…”

Approaching C1 Reaction Mechanisms Using Combined Operando and Transient Analysis: A Case Study on Cu/CeO2 Catalysts during the LT-Water–Gas Shift Reaction

“…It is therefore of great importance to find efficient and cost-effective WGS catalysts that run efficiently even at low temperatures (<200 °C). Metal-loaded ceria has been proven to be a good alternative to the conventional copper–zinc oxide catalysts used in industry, − but important aspects such as the reaction mechanism, the role of the metal, and the influence of the ceria support properties are still a matter of debate.…”

Reversible Growth of Gold Nanoparticles in the Low-Temperature Water–Gas Shift Reaction

“…Such an approach has been successfully applied to monitor changing Au species over Au/CeO 2 catalysts during CO oxidation and regeneration. 12 …”

“…Therefore, we employed operando XAS to measure the change in the catalyst structure under working conditions. Such an approach has been successfully applied to monitor changing Au species over Au/CeO 2 catalysts during CO oxidation and regeneration …”