Praseodymium Oxide Modified CeO2/Al2O3 Catalyst for Selective Catalytic Reduction of NO by NH3

A series of CeO2/Al2O3 catalysts 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 NH3 to screen suitable addition of praseodymium oxide. These samples were characterized by XRD, N-2-BET, NH3-TPD, NO-TPD, Py-IR, H-2-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 degrees 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 Al2O3 crystal 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.