Modification Effect of Pt on the Active Sites of Sulfated CeO2 Nanorods for the Selective Catalytic Reduction of NO

Although the surface acidity of CeO2 has been increased by H2SO4 to increase its acid sites, the low-temperature (<250 °C) activity of sulfated CeO2 catalysts still needs to be improved. In this study, a Pt-modified CeO2 catalyst was prepared by impregnation or reduction methods to increase its catalytic activity. The results showed the Pt-modified CeO2 catalyst significantly widened its low-temperature catalytic window. The NO conversion and N2 selectivity of the Pt1.0%/SCe-I sample were both more than 90% at 200–350 °C because of its numerous acid sites, excellent redox ability, and higher Pt2+ content. NH3, NH4+, –NH2, and bridging nitrates and monodentate nitrates on the Pt1.0%/SCe-I catalyst surface acted as the active substances. Among them, coordinated NH3 at the Lewis acid sites reacted first. This study highlights the interactions among metals, sulfates, and carriers and supplies a useful method to improve the low-temperature activity of sulfated CeO2.