The Pt-Ba Interaction in Lean NOx Trap Systems

In a previous systematic investigation on the adsorption of NO_x/O₂ over Pt/Al₂O₃, Ba/Al₂O₃ and Pt-Ba/Al₂O₃ samples, a novel pathway for NO_x storage was proposed that implies the direct uptake of NO in the presence of oxygen in the form of nitrites at Ba sites nearby Pt. In order to better elucidate the role of the Pt-Ba interaction on NO_x storage and reduction, in the present study the adsorption of NO_x/O₂ and their subsequent reduction was further investigated over Pt-Ba/Al₂O₃ samples having different Ba loadings; a physical mixture Pt/Al₂O₃+Ba/Al₂O₃ was also considered for comparison purposes. A kinetic literature model has been adapted to our catalytic system in order to simulate the transient NOx adsorption over a wide range of operating conditions.