Size effect of Pt nanoparticles on the catalytic oxidation of toluene over Pt/CeO2 catalysts

The present work elucidated the size effect of Pt nanoparticles on the activity of Pt/CeO2 catalysts toward catalytic oxidation of toluene. Size-controllable Pt nanoparticles, ranging from 1.3 to 2.5 nm, were successfully loaded on CeO2 nanorod support by the adsorption method. The structure and chemical properties of Pt/CeO2 catalysts are much dependent on Pt particle size. As size increases, the Pt dispersion declines while more Pt-OCe bonds, Ce3+ and oxygen vacancies exist on ceria. The catalytic activity test of toluene oxidation shows that Pt/CeO2-1.8 sample exhibits the best catalytic performance due to the balance of both Pt dispersion and oxygen vacancy concentration of ceria. Three types of TOFs values based on Pt dispersion, oxygen vacancy concentration and both of them are calculated respectively, and the result demonstrates that the reaction rate is controlled by both of the exposed Pt atom and oxygen vacancies. In addition, the Pt/CeO2-1.8 catalyst could work properly for 120 h with various inlet toluene concentration and be completely negligible for 5 vol% water vapour at 155 °C.