SO2 Resistance of Mn–Ce Catalysts for Lean Methane Combustion: Effect of the Preparation Method

Various catalysts were synthesized by the redox-precipitation (RP) and co-precipitation (CP) methods, and SO2 resistance of the catalysts for lean methane combustion was furtherly investigated. The catalysts before and after the reaction were characterized by XRD, XPS, SEM, FTIR, and H2-TPR. Under the circumstance of 80 ppm SO2, the methane conversion of MnCe-RP reduced by 1.08% within 20 h, much more excellent SO2 resistance than MnCe-CP (reduced by 62.45%). The excellent SO2 resistance of MnCe-RP was due to the excellent morphology, the redox-potential and the SO2 uptake of KxMn8O16 in the bulk and on the surface, oxidizing SO2 to sulfides, protecting the downstream catalyst. And the various sulfates were detected by X-ray diffraction (XRD) and Fourier transform-infrared spectroscopy (FT-IR), and reduced the activating sites of the catalysts. This work provided a general strategy to enhance SO2 resistance of the catalyst system for lean methane catalytic combustion, utilizing KxMn8O16 to remove SO2 and free from the poison of the downstream catalyst.