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.