IMPURITY AND SUPPORT EFFECTS ON SURFACE COMPOSITION AND CO+NO REACTIONS OVER Pt–Rh/CeO2 NANOPARTICLES: A COMPARATIVE STUDY

A Monte Carlo simulation technique has been used to investigate the effect of sulphur impurity and ceria support on the surface composition and catalytic activity of Pt–Rh /ceria nanocatalysts. For temperatures in the range of 400–1300 K the surface Pt concentration decreases with increase in sulphur coverage. The Pt concentration at the base of the nanocatalyst in contact with the support increases with metal-support interaction. However, for weak metal-support interaction (V ms <-0.01 eV ) the surface Pt concentration slightly increases with metal-support interaction. Overall, sulphur is found to influence the surface composition much more strongly than the metal-support interaction. The MC-simulated surface composition results have been used to study the energetics of the CO+NO reactions over Pt–Rh/CeO 2 catalysts. It is found that the CO 2 formation rate decreases with increase in sulphur coverage and marginally increases with metal-support interaction up to V ms =-0.01 eV . All the results qualitatively agree with the experimental results.