Enhanced catalytic performance of Ce-MCM-41-supported Rh for CO oxidation
1wt%Rh/Ce-MCM-41 catalysts were prepared by the incipient wet impregnation method using mesoporous Ce-MCM-41 materials as supports where the Si/Ce molar ratios varied from 10 to 50. The structural properties and physicochemical features of the catalysts were characterized with a variety of technique...
Gespeichert in:
Veröffentlicht in: | Research on chemical intermediates 2021-07, Vol.47 (7), p.2857-2880 |
---|---|
Hauptverfasser: | , , , , , |
Format: | Artikel |
Sprache: | eng |
Schlagworte: | |
Online-Zugang: | Volltext |
Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
Zusammenfassung: | 1wt%Rh/Ce-MCM-41 catalysts were prepared by the incipient wet impregnation method using mesoporous Ce-MCM-41 materials as supports where the Si/Ce molar ratios varied from 10 to 50. The structural properties and physicochemical features of the catalysts were characterized with a variety of techniques such as N
2
physisorption, X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The CO adsorption–desorption behaviors on the catalysts were explored with in situ Fourier-transform infrared (FTIR) spectroscopic technique. The light-off curves of CO oxidation achieved on the Rh/Ce-MCM-41 catalysts significantly shifted toward lower temperature range compared to that achieved with the Rh/CeO
2
and Rh/MCM-41 reference catalysts. The Rh/Ce-MCM-41 catalysts exhibited high activity with complete CO conversion at temperatures near 440 K. The in situ CO-FTIR spectra confirmed that several forms of Rh−O, Rh
2
−CO, Rh
3
−CO and Rh−(CO)
2
carbonyl species with linear, bridged, hollow and
gem
-dicarbonyl bonds were formed. CO preferentially adsorbs on highly dispersed Rh clusters to form
gem
-dicarbonyl species. A reaction mechanism was proposed based primarily on the formation of intermediary species of CO adsorbed over Rh
3+
clusters and the active O···OH oxygen species present on the surface in combination with the incorporation of Ce
4+
ion into the framework of MCM-41 material. These findings suggest that the deposition of the Rh phase on the ceria-modified mesoporous supports could remarkably promote CO oxidation at low temperatures. |
---|---|
ISSN: | 0922-6168 1568-5675 |
DOI: | 10.1007/s11164-021-04436-4 |