Ce–Zr–Mn Oxide Catalysts for Soot Combustion: The Role of Preparation Method

In catalysis science and technology, the catalytic performance of materials is strongly dependent on the preparation method used. The catalysts with similar composition can show significantly different performance, while the causing factors remain debated. Here, we show the effect of preparation methods on the soot combustion performance of ternary MnOx–CeO2–ZrO2 catalysts prepared by a citric acid-assisted method and the solvothermal approach utilizing propionic acid. In both series of catalysts, the Tmax of soot combustion changes in a row: CeO2–MnOx < CeO2 < CeO2–ZrO2–MnOx < CeO2–ZrO2, and the catalyst components, regardless of their form and distribution within the sample, feature synergistic effects in the soot combustion reaction. A notable decrease in the soot combustion temperature is observed for all samples prepared by the solvothermal approach as compared to the citrate series, which is caused by the enhanced interphase air-catalyst-soot interaction, resulting in the formation of an interfacial structure of the "Mn–O–Mn–O–Ce" type, generation of oxygen vacancies, and reoxidation of active oxide species at the MnOx/CexZr1–xO2 interfaces.