Influence of preparation methods on the physicochemical properties and catalytic performance of Mn-Ce catalysts for lean methane combustion

Various catalysts were synthesized by the redox-precipitation (RP) and co-precipitation (CP) methods, and their catalytic performances for the complete catalytic oxidation of lean methane combustion were investigated. The synthetic catalysts were characterized by BET, XRD, Raman, XPS, TG, UV–vis and H2-TPR. MnCe-RP showed 50% methane conversion to CO 2 at ˜446 °C, which was 23 °C lower the temperature required for MnCe-CP. The active components (K x Mn 8 O 16 ) in the bulk and on the surface of MnCe-RP were confirmed. The redox-precipitation method synthesized open nanorod and nanosphere catalysts containing K x Mn 8 O 16 and Mn 5 O 8 , whereas the co-precipitation method synthesized agglomerate catalysts containing only Mn 5 O 8 . The higher surface-concentrations of Mn 4+ , Ce 3+ and O α on MnCe-RP are beneficial for its higher catalytic performance. Furthermore, the optical bandgap value of MnCe-RP is lower than that of MnCe-CP, and the K ion in K x Mn 8 O 16 may weaken the Mn-O bond, improving the catalyst reducibility, especially for the reduction process of Mn 3 O 4 →MnO.