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 CO2 at (similar to)446 degrees C, which was 23 degrees C lower the temperature required for MnCe-CP. The active components (KxMn8O16) in the bulk and on the surface of MnCe-RP were confirmed. The redox-precipitation method synthesized open nanorod and nanosphere catalysts containing KxMn8O16 and Mn5O8, whereas the co-precipitation method synthesized agglomerate catalysts containing only Mn5O8. The higher surface-concentrations of Mn4+, Ce3+ and O-alpha 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 KxMn8O16 may weaken the Mn-O bond, improving the catalyst reducibility, especially for the reduction process of Mn3O4 -> MnO.