Catalytically Active and Spectator Ce super(3+) in Ceria-Supported Metal Catalysts

Identification of active species and the rate-determining reaction steps are crucial for optimizing the performance of oxygen-storage materials, which play an important role in catalysts lowering automotive emissions, as electrode materials for fuel cells, and as antioxidants in biomedicine. We demo...

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Bibliographic Details
Published in:Angewandte Chemie 2015-07, Vol.127 (30), p.8852-8855
Main Authors: Kopelent, Rene, vanBokhoven, Jeroen A, Szlachetko, Jakub, Edebeli, Jacinta, Paun, Cristina, Nachtegaal, Maarten, Safonova, Olga V
Format: Article
Language:English
Subjects:
Catalysis
Catalysts
Cobalt
Electrode materials
Emission spectroscopy
Oxidation
Reduction
Spectators
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Summary:Identification of active species and the rate-determining reaction steps are crucial for optimizing the performance of oxygen-storage materials, which play an important role in catalysts lowering automotive emissions, as electrode materials for fuel cells, and as antioxidants in biomedicine. We demonstrated that active Ce super(3+) species in a ceria-supported platinum catalyst during CO oxidation are short-lived and therefore cannot be observed under steady-state conditions. Using time-resolved resonant X-ray emission spectroscopy, we quantitatively correlated the initial rate of Ce super(3+) formation under transient conditions to the overall rate of CO oxidation under steady-state conditions and showed that ceria reduction is a kinetically relevant step in CO oxidation, whereas a fraction of Ce super(3+) was present as spectators. This approach can be applied to various catalytic processes involving oxygen-storage materials and reducible oxides to distinguish between redox and nonredox catalytic mechanisms.Original Abstract: Kurzlebiges Ce super(3+) ist das kinetisch relevante Zwischenprodukt in der katalytischen CO-Oxidation auf einem Ceroxid-getraegerten Metallkatalysator, waehrend langlebige Ce super(3+)-Spezies unbeteiligte Zuschauer sind. Dies wurde durch In-situ-Resonanz-Rontgenemissionsspektroskopie und die quantitative Korrelation zwischen der Anfangsgeschwindigkeit der Ce super(3+)-Bildung unter transienten Bedingungen und der Gesamtgeschwindigkeit der CO-Oxidation gezeigt.
ISSN:0044-8249
1521-3757
DOI:10.1002/ange.201503022