Abstract:
The Co
3O
4@MnO
x monolithic catalyst with nanorod morphology was synthesized on nickel foam by a two-step hydrothermal process and characterized by XRD, EDS-mapping, H
2-TPR, XPS, Raman and Soot-TPR. The catalytic soot combustion activities of the catalysts were investigated in a fixed-bed micro-reactor and the intrinsic activities of the catalysts were investigated by the isothermal kinetic experiments. The results reveal that the Co
3O
4@MnO
x catalyst shows a core-shell structure with Co
3O
4 as the core and MnO
x as the shell. Compared with Co-NW, there exist more high-valent state species of Mn
4+ and Mn
3+ and oxygen vacancies on the Co
3O
4@MnO
x catalyst surface due to the interaction between Co
3O
4 and MnO
x, which improve the redox performance of Co
3O
4@MnO
x. Compared with Co-NW, the active oxygen species amount of Co
3O
4@MnO
x is increased by two times, and Co
3O
4@MnO
x shows enhanced activity, which lowers the ignition temperature by 148 ℃ in the presence of NO. Also, compared with Co-NW, Co
3O
4@MnO
x decreases the activation energy of soot combustion reaction from 113.6 to 102.2 kJ/mol, and its intrinsic activity is increased by two times.