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New insights on the defect sites evolution during CO oxidation over doped ceria nanocatalysts probed by in situ Raman spectroscopy.
- Source :
-
Applied Catalysis A: General . Apr2020, Vol. 596, pN.PAG-N.PAG. 1p. - Publication Year :
- 2020
-
Abstract
- • CO oxidation was studied by in situ Raman spectroscopy on nanostructured ceria-based materials. • In situ Raman analyses during CO oxidation allowed to monitor defect sites in operando conditions. • Cycles of reduction (CO in N 2) and oxidation (pure O 2) at 400 °C allow to study the stability of defects. • Oxygen vacancies evolved from clusters to isolated ones according to the atmosphere and temperature. • The involvement of the defect sites in structural rearrangement is fostered by easily reducible dopants. Among the factors affecting ceria activity, the defectiveness plays a key role in the case of CO oxidation. In this study, its connection with the catalytic performance was investigated via in-situ Raman spectroscopy on nanostructured pure and Cu/Mn-doped ceria, monitoring the defect sites and surface species evolution during the reaction. The accumulation of polyene-like chains, formed through CO dissociative adsorption at the catalyst surface, was observed and their disappearance was related to the catalyst light-off temperature. Moreover, the doped samples exhibited a rise of the Raman bands associated to defects after the tests, consequence of the structural rearrangements occurring during CO oxidation. Indeed, in-situ Raman measurements during reduction (CO/N 2) and oxidation cycles at 400 °C evidenced the formation of oxygen vacancy clusters in reducing atmosphere, which could reorganize not only in O 2 but also upon a temperature decrease, forming isolated vacancies and then evolving in Frenkel and extrinsic oxidized dopant-containing sites when exposed to oxygen. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 0926860X
- Volume :
- 596
- Database :
- Academic Search Index
- Journal :
- Applied Catalysis A: General
- Publication Type :
- Academic Journal
- Accession number :
- 142792536
- Full Text :
- https://doi.org/10.1016/j.apcata.2020.117517