Praseodymium Oxide Modified CeO₂/Al₂O₃Catalyst for Selective Catalytic Reduction of NO by NH₃

A series of CeO₂/Al₂O₃catalysts was modified with praseodymium oxide using an extrusion method. The catalytic activities of the obtained catalysts were measured for the selective catalytic reduction of NO with NH₃to screen suitable addition of praseodymium oxide. These samples were characterized by XRD, N₂-BET, NH₃-TPD, NO-TPD, Py-IR, H₂-TPR, Raman spectra and XPS, respectively. Results showed the optimal catalyst with the Pr/Ce molar ratio of 0.10 exhibited more than 90% NO conversion in a wide temperature range of 290–425°C under GHSV of 5000 h⁻¹. The number of Lewis acid sites and the chemisorbed oxygen concentration of the catalysts would increase with the Pr incorporation, which was favorable for the excellent catalytic performance. In addition, the Pr incorporation inhibited growth of the Al₂O₃crystal particles and led to the lattice expansion of CeO₂, which increased catalytic activity. The results implied that the higher chemisorbed oxygen concentrations and the more Lewis acid sites were conductive to obtain the excellent SCR activity.