Manganese promoted TiO2 and ZrO2 nanostructures for soot combustion with boosted efficiency

Abstract TiO2, ZrO2 and mixed-oxide (TiO2-ZrO2) materials with manganese as active promoter were synthesized. The performance of these catalysts was tested in the diesel soot oxidation reaction. The soot conversion light-off temperature was remarkably lowered by manganese in the mixed-oxide (TiO2-ZrO2) in comparison with manganese in the TiO2 and ZrO2 catalysts. On the other hand, the mixed oxide enhanced surface defects because of the promotional role played by the ZrO2 interface, which led to the formation and stabilization of defect sites. In addition, the O2/TPD characterization revealed two peaks corresponding to desorption of oxygen species and desorption of lattice oxygen between 120 and 500 °C, which was correlated with the catalytic activity. The manganese-doped-mixed-oxide (TiO2-ZrO2) catalyst displayed structural stability, higher surface area, presence of Mn3+ and Mn4+ species and soot conversion light-off temperature of 260 °C, which was preserved after three reaction cycles.