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

Although the surface acidity of CeO 2 has been increased by H 2 SO 4 to increase its acid sites, the low-temperature (<250 °C) activity of sulfated CeO 2 catalysts still needs to be improved. In this study, a Pt-modified CeO 2 catalyst was prepared by impregnation or reduction methods to increase its catalytic activity. The results showed the Pt-modified CeO 2 catalyst significantly widened its low-temperature catalytic window. The NO conversion and N 2 selectivity of the Pt 1.0% /SCe-I sample were both more than 90% at 200–350 °C because of its numerous acid sites, excellent redox ability, and higher Pt 2+ content. NH 3, NH 4+, –NH 2, and bridging nitrates and monodentate nitrates on the Pt 1.0% /SCe-I catalyst surface acted as the active substances. Among them, coordinated NH 3 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 CeO 2 .