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 CeFeOx, FeOx, CeOx, 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/CeFeOx/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.