High-temperature vanadium-free catalyst for selective catalytic reduction of NO with NH3 and theoretical study of La2O3 over CeO2/TiO2

Abstract

The high-temperature SCR catalyst La₂O₃–CeO₂/TiO₂ was prepared by an impregnation method. The effect of CeO₂ and La₂O₃ content on NO conversion was studied and the experimental result showed that the Ce₁₀La₂ catalyst had the best catalytic activity and aging resistance. The active temperature range of the Ce₁₀La₂ catalyst is higher than 355 °C. The as-prepared catalysts were characterized by different methods. The introduction of La₂O₃ increases the specific surface area, the dispersion of CeO₂, and the number of strong acid sites of the catalyst. La₂O₃ interacts with CeO₂ to form the Ce–O–La bond on the CeO₂ surface rather than forming a solid solution, which increases the concentration of Ce³⁺ and the surface unsaturated active oxygen, thus improving the catalytic activity. In situ DRIFTS shows that the denitration reaction is dominated by the Eley–Rideal mechanism. Density functional theory calculation shows that the adsorption of NO or NH₃ on the CeO₂ surface becomes easier after the introduction of La₂O₃.