Advanced MnOx/TiO2 Catalyst with Preferentially Exposed Anatase {001} Facet for Low-Temperature SCR of NO

Abstract

MnOx/TiO2 (anatase) nanosheets (NS) with a preferentially exposed {001} facet was found to be a better catalyst for selective catalytic reduction (SCR) of NO than conventionally employed MnOx/TiO2 nanoparticles (NP) with the {101} facet preferentially exposed, affording both high NO conversion and high N2 selectivity at 80–280 °C. Further investigations indicated that Mn3+ as the major species on TiO2 (NS) was incorporated into octahedral vacancies with a lower polymerization degree, resulting in high catalytic activity for SCR and low activity for NH3 oxidation, thus restraining the undesirable N2O generation. In comparison, on the surface of TiO2 (NP), Mn4+ as the major species was incorporated into tetrahedral vacancies in a highly polymerized state, leading to lower NO conversion and lower N2 selectivity. The results indicate that it is possible to enhance the low-temperature SCR activity of the catalysts by tailoring the preferentially exposed facet of TiO2.