Highly active urchin-like MCo2O4 (M = Co, Cu, Ni or Zn) spinel for toluene catalytic combustion

MCo2O4 (M = Co, Cu, Ni or Zn) spinel catalysts have been prepared using a chemical co-precipitation method and applied in toluene combustion. The physicochemical properties of the MCo2O4 catalysts was discussed to explore the impact of substitution on the tetrahedral A-site ions. The results of the activity evaluation show that the catalytic performances of Co3O4, CuCo2O4 and NiCo2O4 with urchin-like morphology are far superior than ZnCo2O4 nanoparticles. The CuCo2O4 catalyst exhibited the most superior performance for toluene combustion, and the toluene conversion rate reached 90% at 230 °C. When compared to the other catalysts, the optimal activity of CuCo2O4 was attributed to the presence of more reactive oxygen species, a higher concentration of Co3+ ions on catalyst surface and better reducibility at relative lower temperature. Moreover, the catalytic activity of the CuCo2O4 catalyst did not decrease significantly in the long-term test, demonstrating its excellent stability.