Manganese oxide nanorod catalysts for low-temperature selective catalytic reduction of NO with NH 3 .

MnO x nanorod catalysts were successfully synthesized by two different preparation methods using porous SiO 2 nanorods as the template and investigated for the low-temperature selective catalytic reduction (SCR) of NO with NH 3 . The catalysts were characterized by scanning electron microscopy, transmission electron microscopy, nitrogen adsorption, X-ray diffraction, X-ray photoelectron spectroscopy, and NH 3 temperature-programmed desorption. The results show that the obtained MnO x -P nanorod catalyst prepared by redox precipitation method exhibits higher NO removal activity than that prepared by the solvent evaporation method in the low temperature range of 100-180 °C, where about 98% NO conversion is achieved over MnO x (0.36)-P nanorods. The reason is mainly attributed to MnO x (0.36)-P nanorods possessing unique flower-like morphology and mesoporous structures with high pore volume, which facilitates the exposure of more active sites of MnO x and the adsorption of reactant gas molecules. Furthermore, there is a lower crystallinity of MnO x , higher percentage of Mn 4+ species and a large amount of strong acid sites on the surface. These factors contribute to the excellent low-temperature SCR activity of MnO x (0.36)-P nanorods.