Enhanced catalytic oxidation of soot over 3DOM LaMnO3 by adding Ag and CeO2: Improving the generation and delivery of active oxygen species

• Ag and CeO 2 were embedded in 3DOM LaMnO 3 by redox etching precipitation method. • Ag introduced by redox etching precipitation had higher degree of dispersion. • Ag improved O 2 – generation but decreased the oxygen vacancies of 3DOM LaMnO 3 . • CeO 2 could deliver O 2 – produced on Ag while induced more oxygen vacancies. • Excellent catalytic activity was obtained with optimal Ag content. In this work, Ag-Ce modified 3DOM LaMnO 3 catalysts were first synthesized by redox etching precipitation and used for NO x -assisted soot oxidation. Compared with wetness impregnation method, Ag introduced by redox etching precipitation method showed smaller size and stronger interaction with 3DOM LaMnO 3 , thus presented better catalytic performance. Moreover, Ag content was selected as variable (Ag mass ratio = 1–5 wt%) to explore the role of Ag in catalytic soot oxidation. The characterization results had demonstrated that Ag could activate oxygen and convert it into highly active superoxide species (O 2 – ). Besides, Ag could enhance the oxygen mobility and NO 2 consumption rate, leading to better activity for NO x -assisted soot oxidation. However, excessive Ag (>4 wt%) would cause too low oxygen vacancy amount, causing worse catalytic performance. Further modification with CeO 2 mainly increased oxygen vacancy and transferred O 2 – produced on Ag. Besides, NO 2 utilization rate were further enhanced. Hence, 4Ag-Ce/LM with optimal Ag amount exhibited the best catalytic activity for NO x -assisted soot oxidation with T 50 value of 367 ℃. Moreover, it also showed good reusability and water resistance. This work synthesized a promising catalyst for soot oxidation and was expected to offer a new insight for catalyst design in other fields.