Preparation of Fe-doped Octahedral Layered Birnessites Catalysts and the Catalytic Oxidation of CO

To effectively remove CO from atmospheric pollutants, the octahedral layered birnessites (MnO_x-L) was prepared by a redox method, and Fex/MnO_x-L samples with different mass fractions of Fe loading were prepared by ion exchange method. Physicochemical properties of the samples were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) technique, BET (specific surface area measurement), thermogravimetric analysis (TGA), hydrogen temperature programmed reduction (H₂-TPR), oxygen temperature-programmed desorption (O₂-TPD), X-ray photoelectron spectroscopy (XPS) techniques. MnO_x-L support was a typical octahedral birnessites structure. Fe loading did not affect the support structure, but influenced their physical and chemical properties. The reduction of the catalyst and the ratio of m(Fe²⁺)/m(Fe³⁺) and m(O_ads)/m(O_latt) on the surface changed, as well as the catalytic activity significantly improved after loading iron. Among Fex/MnO_x-L samples, Fe5/MnO_x-L showed the best reducibility, oxygen mobility, and the highest ratio of m(Fe²⁺)/m(Fe³⁺) and surface adsorption oxygen. Fe5/MnO_x-L showed the best catalytic activity (t₅₀=80℃ and t₉₀=150℃) for CO oxidation, related to the interaction between Fe species and MnO_x-L.