Promoting the generation of active oxygen species on 3DOM K/LaMnO3 interface by introducing CeO2 to boost the NOx-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 NOx-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 Ea 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.