Promoting the generation of active oxygen species on 3DOM K/LaMnO₃ interface by introducing CeO₂ to boost the NO_x-assisted soot combustion

Herein, a series of K, Ce modified 3DOM LaMnO₃ catalysts, named K/xCe/LM (x = 0, 10, 15 and 20 wt%) had been prepared and used for NO_x-assisted soot oxidation. 3DOM LaMnO₃ employed as the matrix could offer an ideal environment to hinder the agglomeration of CeO₂. Meanwhile, introducing CeO₂ on the surface of LaMnO₃ would drive the generation of Mn⁴⁺ and Ce³⁺ through the redox cycle of Ce⁴⁺ + Mn³⁺ ↔ Mn⁴⁺ + Ce³⁺, which was conclusive to the generation of oxygen vacancy. Further modification of xCe/LM catalysts with K could accelerate the redox cycle, generating more active oxygen species and enhance the NO₂ utilization rate during the reaction. It was noted that high content of CeO₂ would aggregate and plug the macropores, leading to a decrease in catalytic activity. Among all the catalysts, K/15Ce/LM samples with optimal Ce content demonstrated the best catalytic performance. The T₅₀, TOF and E_a values were 377 ℃, 3.30 × 10^-3 s⁻¹ and 57 kJ·mol⁻¹, respectively. Besides, K/15Ce/LM catalysts also possessed excellent reusability, structure stability and water-resistance. The implementation of this work might offer a significant insight into the fabrication of high-performance soot oxidation catalyst for practical application.