Insight into the synergism between MnO(2) and acid sites over Mn–SiO(2)@TiO(2) nano-cups for low-temperature selective catalytic reduction of NO with NH(3)

The rational synthesis of low-temperature catalysts with high catalytic activity and stability is highly desirable for the selective catalytic reduction of NO with NH(3). Here we synthesized a Mn–SiO(2)/TiO(2) nano-cup catalyst via the coating of the mesoporous TiO(2) layers on SiO(2) spheres and subsequent inlay of MnO(2) nanoparticles in the narrow annulus. This catalyst exhibited superior catalytic SCR activities and stability for low-temperature selective catalytic reduction of NO with NH(3), with NO conversion of ∼100%, N(2) selectivity above 90% at a temperature ∼140 °C. The characterization results, such as BET, XRD, H(2)-TPR, O(2)/NH(3)-TPD and XPS, indicated that this nano-cup structure catalyst possesses high concentration and dispersion of Mn(4+) active species, strong chemisorbed O(−) or O(2)(2−) species and highly stable MnO(X) active components over the annular structures of the TiO(2) shell and SiO(2) sphere, and thus enhanced the low-temperature SCR performance.