Effect of Doped Ag on Performance of Manganese Oxide Octahedral Molecular Sieve for CO Oxidation

A series of Ag-doped manganese oxide octahedral molecular sieves (OMS-2) were synthesized by the reflux method in an acid medium. The structure of the catalysts was characterized by X-ray diffraction, N2 adsorption, transmission electron microscopy, and temperature-programmed desorption (TPD). The effect of the promoter Ag was deduced. The results showed that the catalysts have the typical cryptomelane structure with a one-dimensional channel. The doping with Ag resulted in Ag/OMS-2 catalysts with a higher specific surface area and narrower pore size distribution than OMS-2. The catalysts showed excellent catalytic activity for CO oxidation and the catalytic activity was increased after Ag introduction. O2-TPD and CO-TPD results showed that this was because the doping with Ag increased the rate of CO adsorption and the diffusion of lattice oxygen ions.