Low-temperature NO oxidation over Mn/TiO2 nanocomposite synthesized by chemical vapor condensation: Effects of Mn precursor on the surface Mn species

Abstract

Mn/TiO2 nanocomposite materials for low-temperature selective NO oxidation was prepared through the impregnation of manganese acetate or manganese nitrate precursors on TiO2 particles fabricated by chemical vapor condensation. Improved low-temperature NO conversion resulted when manganese acetate precursor was used: NO oxidation activity was maximized at 88% at 225°C. The materials were characterized by BET, XRD, HR-TEM, XPS and H2-TPR. The increased activity was attributed to the manganese acetate precursor providing well-dispersed Mn species on the material’s surface and increasing its surface area. Abundant Mn3+ species, hydroxyl groups, increased oxygen linking to Mn, and high concentrations of amorphous Mn on the surface resulted in the material’s improved activity towards NO oxidation at lower temperatures.