Influence of Co-Ni interactions on catalytic activity of xCo/NiO nanosheet catalysts in situ grown on monolithic cordierite for soot combustion

Abstract

Co3O4-loaded NiO monolithic catalysts were successfully prepared on cordierite substrates using a simple hydrothermal and impregnation method. The mass transfer of gaseous reactants and products during soot combustion is facilitated by the constructed macroporous voids, thereby enhancing the soot-catalyst contact efficiency. The results demonstrate that the interaction of Ni and Co (Co2+ + Ni3+ ↔ Ni2+ + Co3+) leads to an increase in the amount of Co3+ cations, resulting in a higher quantity of oxygen vacancies. Besides the surface adsorbed oxygen (Oads), it demonstrates that the hydroxyl group (-OH) also acts as active oxygen species in soot oxidation. And, the impact of Co loading on the catalysts displays a volcano-type on the performance of soot oxidation. 0.5Co/NiO with the strongest CO-Ni interaction possesses the highest intrinsic activity. As a result, 0.5Co/NiO shows the highest activity with T50 at 382 °C in 600 ppm NO/10 % O2/N2 flow, as well as high stability and water resistance. Moreover, the prepared catalysts can efficiently catalyze NO to NO2, which possesses higher reactivity for soot oxidation than O2 and NO. Consequently, the as-designed Co/NiO monolithic catalysts hold great potential for applications in soot combustion and other non-homogeneous catalytic systems.