Catalytic combustion of dimethyl ether over Ce-doped cryptomelane-type manganese oxide

Manganese oxide octahedral molecular sieves (OMS-2) were synthesized by oxidizing MnSO₄ with KMnO₄ and then doped with Ce. The structure and oxidation activity of the catalysts were characterized by XRD, N₂ adsorptiondesorption, TEM, FT-IR, Uv-vis, O₂-TPD, H₂-TPR and XPS techniques. The catalytic activity for dimethyl ether (DME) combustion was also evaluated. The results showed that the highly-dispersed amorphous CeO₂ exited when Ce-doping was low. However, the independent CeO₂ formed when Ce-doping exceed 10%. XPS results show that the doped-Ce can improve the lattice oxygen of the catalyst. O₂-TPD and H₂TPR characterization show that the Ce-OMS-2 catalysts have abundant facile lattice oxygen and can be easily reduced. Ce-OMS-2 display excellent performance in DME catalytic combustion, with a start-off temperature of 160℃ and a complete temperature of 170℃. CO₂ and H₂O are the only reaction products detected. The used catalyst keeps the same crystalline as the fresh, and there is no carbon deposition detected over the used catalyst.