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 degrees C. The materials were characterized by BET, XRD, HR-TEM, XPS and H-2-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. (C) 2012 Elsevier Inc. All rights reserved.