CO and CH4 Oxidation Reactions on Pt/CeO2 Catalysts: Experimental Study and Mathematical Modeling

CO and CH₄ oxidation reactions on Pt/CeO₂ catalysts were studied with the aid of experimental kinetic methods of temperature-programmed reactions with CO and CH₄ in combination with modeling of the reaction kinetics. The comparison of results obtained for catalysts with low and high Pt content made it possible to differentiate the features of CO and CH₄ interaction with different active centers of the catalyst surface, namely, single atoms and PtO_x clusters. The presence of PtO_x clusters in catalysts leads to the implementation of low-temperature reactions CO + O₂ and CH₄ + O₂. The developed scheme of reactions at the boundary and internal centers of clusters made it possible to explain the implementation of both partial and complete oxidation of methane. When modeling the methane oxidation reaction on PtO_x clusters, it was established that the active centers are the boundary centers of clusters modified with OH-groups, which are formed by the dissociation of methane on Pt-O-Ce centers. The experimentally observed increase in the catalytic activity of the methane oxidation reaction in the presence of CO is associated with an additional CO-assisted O₂ dissociation mechanism, which is realized only on PtO_x cluster centers and not realized on single atom sites.