Catalytic combustion of dimethyl ether over α-MnO2 nanostructures with different morphologies

Abstract

Herein, α-MnO2 catalysts with three well-defined morphologies (nanorod, ultra-long nanowire and microsphere) were rational designed and prepared by the hydrothermal route, and their catalytic activities were evaluated for the dimethyl ether (DME) combustion. These nanostructured α-MnO2 catalysts were characterized in detail by various analytical techniques: XRD, FESEM, TEM, BET, XPS and H2-TPR. As a result, the α-MnO2 nanorod exhibited the higher catalytic activity (T10=170°C and T90=238°C at WHSV=30,000mLg−1h−1) than the other two α-MnO2 samples due to its larger specific surface area, higher average oxidation state of Mn, more abundant surface lattice oxygen (Olatt) species and higher reducibility, and there was no obvious decrease after the α-MnO2 nanorod was run for 50h. Moreover, the transient response technique revealed that the Olatt species of the α-MnO2 nanorod should be the crucial role in the deep oxidation of DME.