Efficient Pt/Ba/Sn_xCe_1–xO₂ Catalysts for High-Temperature Lean NO_x Traps with High H₂O and CO₂ Tolerance

Abstract

Herein, we investigate the De-NO x activity of Pt/Ba/Sn x Ce1–x O2 catalysts at high temperatures. Our results show that at high temperatures, their NO x storage capacity (NSC), linked to the quantity of highly dispersed BaCO3 species on the catalysts, determines the De-NO x activity instead of the NO x 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 NO x 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 NO x storage period. Thus, it exhibits the superior De-NO x performance with NO x removal percentage over 86% in the presence of H2O and CO2 at 350∼500 °C.