Sensitivity of CO oxidation toward metal oxidation state in ceria-supported catalysts: an operando DRIFTS-MS study
Résumé
The oxidation of carbon monoxide has been studied on pristine CeO2,
Rh-CeO2, and Pt-CeO2 powders prepared in one step by solution combustion
synthesis (SCS). The reaction was cycled between an oxygenrich and a
CO-rich feed with regard to the stoichiometric conditions. CO2
production was monitored by mass spectrometry, while the surface species
were probed by operando DRIFTS (Diffuse Reflectance Infrared Fourier
Transform Spectroscopy). Whereas the reaction starts above 150 degrees C
on CeO2 and Rh-CeO2 and does not depend on the state of the surface
(oxidized or reduced), the reaction on Pt-CeO2 shows strong dependency
on the initial state and substantial activity is achieved at much lower
temperatures with the CO-rich feed. We relate this result to the change
in the oxidation state of Pt via strong interaction with ceria.