Effect of strontium and cerium doping on the structural and catalytic properties of PrMnO3 oxides

Two series of Sr- or Ce-doped PrMnO3 (Pr:Sr/Ce=1−x:x, x=0, 0.2, 0.4, 0.6, 0.8, 1) catalysts were prepared by citric acid sol-gel method. The effect of Ce and Sr on the structure and catalytic properties of PrMnO3 was investigated by means of powder X-ray diffraction, Brunauer-Emmett-Teller analyses and catalytic activity evaluation. The results showed that Sr and Ce could enter into the lattice of the crystal cell and occupy the position of Pr elements to form Pr1−xMxMnO3±λ while the doping ratio x≤0.4. Other phases such as SrMnO3−λ, SrCO3, Mn3O4 and CeO2-MnOx solid solutions appeared due to the insufficient calcination temperature or other factors with a further increase of the doping ratio. These partially substituted perovskites, especially Pr0.6Sr0.4MnO3−λ and Pr0.8Ce0.2MnO3+λ, presented higher catalytic activity and larger specific surface area than PrMnO3. On the other hand, the Ce-doped catalysts showed better results than the Sr-doped ones due to the additional redox contribution of CeO2-based materials.