Dynamic oxygen storage and release over Mn0.1Ce0.9Ox and Mn0.1Ce0.6Zr0.3Ox complex compounds and structural characterization

The dynamic oxygen storage capacity (DOSC) and rate (DOSR) over Mn0.1Ce0.9Ox and Mn0.1Ce0.6Zr0.3Ox prepared by sol–gel method were investigated. The results show that Ce-based compounds containing Mn oxides with variable valences contribute to the majority of DOSC and DOSR performances at low temperature, and the DOSC and DOSR of Mn–Ce–O can be enhanced by the Zr addition at high temperature. Both materials were characterized by XRD, BET, Raman, TPR, EPR and XPS. XRD and Raman results indicate that Mn0.1Ce0.9Ox and Mn0.1Ce0.6Zr0.3Ox are characterized with the fluorite-type cubic structure similar to CeO2, and furthermore the thermal stability of M–Ce–O materials is improved by the introduction of some Zr atoms. EPR researches reveal that there are three types of Mn2+ species: isolated Mn2+ substituting for Ce4+ ions in the lattice with a cubic symmetry, ones in defect with a noncubic symmetry and at the surface of samples. From XPS, it can be concluded that Mn2+/Mn3+ redox couples exist on the surface of Mn0.1Ce0.9Ox and Mn0.1Ce0.6Zr0.3Ox samples.