H2O Promotion of CO Oxidation On Oxidized Pt/CeFeOx.

Steady-state, differential reaction rates for CO oxidation, with stoichiometric O₂:CO feeds, were measured in the presence and absence of H₂O over Pt catalysts supported on thin films of CeFeO_x, FeO_x, CeO_x, and LaFeO₃ that had been deposited on γ-Al₂O₃ by Atomic Layer Deposition. Prior to rate measurements, each catalyst was oxidized and reduced five times at 1073 K. Only the oxidized Pt/CeFeO_x/γ-Al₂O₃ catalyst exhibited significantly increased CO oxidation rates upon the introduction of H₂O. A relatively small deuterium isotope effect was observed and suggests that O–H bond cleavage is not involved in the kinetically relevant step of this process. The nature of the catalyst support, the pretreatment of the catalyst, and the effects of Pt particle size are discussed in relation to the observed H₂O promotion of CO oxidation. [ABSTRACT FROM AUTHOR]