CO- and N2-FTIR characterisation of oxidised Rh species supported on Ce0.68Zr0.32O2.
The identification of a Rh-oxidised species of a Rh(0.29)/Ce0.68Zr0.32O2 catalyst that exhibits peculiar CO-O2 kinetics [I. Manuel, J. Chaubet, C. Thomas, H. Colas, N. Matthess and G. Djéga-Mariadassou, J. Catal. 2004, 224, 269] is addressed. For this purpose, various catalysts are studied by XANES, CO- and N2-FTIR, and benzene hydrogenation. The results obtained, particularly from N2-FTIR, which is, to our knowledge, reported for the first time on this kind of catalyst, suggest that Rh is mainly stabilised as electron-deficient clusters (Rhndelta+) on a Rh(0.29)/Ce0.68Zr0.32O2 catalyst after reduction at 500 degrees C under H2. The existence of these species, which may be caused by either electron perturbation induced on the metal by the reduced support or electron withdrawal from the metal clusters by an inductive effect of the neighbouring Cl anions, is also revealed through CO-FTIR experiments. In the presence of CO, however, evidence of RhI(CO)2 species is also provided.
Fontaine-Gautrelet
Céline
C
Laboratoire de Réactivité de Surface UMR CNRS 7609, Université Pierre et Marie Curie, 4 Place Jussieu, Case, 178, 75252 Paris Cedex 05, France.
Krafft
Jean-Marc
JM
Gorce
Olivier
O
Villain
Françoise
F
Djéga-Mariadassou
Gérald
G
Thomas
Cyril
C