Abstract
Herein, we investigate the De-NOx activity of Pt/Ba/SnxCe1-xO2 catalysts at high temperatures. Our results show that at high temperatures, their NOx storage capacity (NSC), linked to the quantity of highly dispersed BaCO3 species on the catalysts, determines the De-NOx activity instead of the NOx oxidation and reduction ability. Moreover, we identify that monodentate nitrate species are more stable than free ion nitrate species on the Ce-containing catalysts. Thus, the presence of monodentate nitrate species is beneficial to improve the H2O and CO2 tolerance by inhibiting the latter ones' competitive adsorption on NOx storage sites. Compared with other catalysts, Pt/Ba/Sn0.8Ce0.2O2 possesses the larger amount of highly dispersed BaCO3 species, and especially, more monodentate nitrate species are formed on it during the NOx storage period. Thus, it exhibits the superior De-NOx performance with NO removal percentage over 86% in the presence of H2O and CO2 at 350 similar to 500 degrees C.