Enhancement effect of oxygen mobility over Ce0.5Zr0.5O2 catalysts doped by multivalent metal oxides for soot combustion

Ce0.5Zr0.5O2 catalysts promoted by multivalent transition metal (Mn, Fe, Co) oxides have been prepared for accelerating soot combustion. Compared with Ce0.5Zr0.5O2 catalyst, Mnand Co-doped catalysts remarkably improved the catalytic activity of soot combustion, while the Fe-doped catalyst had a slightly effect on soot combustion. TEM, N-2 adsorption-desorption isotherms and XRD were testified to find the correlation between catalytic activity and texture properties, the results revealed that texture properties of prepared catalysts were not sensitive to catalytic activity. However, the more active oxygen species and superior mobility of lattice oxygen species with more oxygen vacancies characterized by XPS, H-2-TPR and O-2-TPD were proved as significant roles on soot combustion after incorporation of various multivalent metals, especially for Mn and Co. Furthermore, Co-doped catalyst with the excellent NO-NO2 conversion capacity visibly reduced soot ignition temperature in 600 ppm NO + 10% O-2 + N-2 under tight contact and loose contact condition due to NO2 is a more effective oxidizing agent than O-2. On the contrary, Fe-doped catalyst with slightly better redox performance and more oxygen vacancies reflected weaker NO oxidation performance than support that might be the reason of abundant adsorbed carbonates inhibiting further adsorption of NO and active oxygen species, which also led to the invisible promoting effect of soot combustion.

Automated summary

Ce0.5Zr0.5O2 catalysts promoted by multivalent transition metal (Mn, Fe, Co) oxides were prepared to accelerate soot combustion. It was found that Mn and Co-doped catalysts significantly improved catalytic activity, while Fe-doped catalyst had a minor effect. Further characterization revealed that active oxygen species and oxygen vacancies played significant roles in enhancing soot combustion, especially for Mn and Co. Co-doped catalyst also exhibited excellent NO-NO2 conversion capacity, leading to reduced soot ignition temperature, whereas Fe-doped catalyst showed weaker NO oxidation performance due to abundant adsorbed carbonates.