Nickel doping MnO2 with abundant surface pits as highly efficient catalysts for propane deep oxidation

Series of nickel doping MnO2 with irregular surface pits were synthesized and employed for propane deep oxidation. The partial substitution of Ni for Mn resulted in the formation of structural defects, which could be observed by high-resolution transmission electron microscopy. The MnNi0.09 sample exhibited the best catalytic activity for propane oxidation with the conversion of 90% at 220 °C. The presence of pits on the MnNi0.09 sample could facilitate the dissociation of propane and mobility of oxygen along the conduction channels of surface pits, thus promoting the catalytic efficiency. Moreover, the in situ studies found that different intermediates were formed on the MnO2 and MnNi0.09 catalysts during the propane oxidation process. The propane was oxidized to propanoyl species on the surface of MnO2 catalyst, while it was oxidized to hydrogen carbonates and carbonates on the surface of MnNi0.09 sample, which were thermally less stable and converted into CO2 at lower temperature. The finding provides a new perspective on understanding the effect of cation doping.