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