Synthesis of K-doped three-dimensionally ordered macroporous Mn0.5Ce0.5Oδcatalysts and their catalytic performance for soot oxidation

A series of K-doped Mn0.5Ce0.5Oδ (K-MCO) catalysts with three-dimensionally ordered macroporous (3DOM) structure and different K loadings were successfully synthesized using simple methods. These catalysts exhibited well-defined 3DOM nanostructure, which consisted of extensive interconnecting networks of spherical voids. The effects of the calcination temperature and calcination time on the morphological characteristics and crystalline forms of the catalysts were systematically studied. The catalysts showed high catalytic activity for the combustion of soot. 3DOM 20% K-MCO-4h catalyst, in particular, showed the highest catalytic activity of all of the catalysts studied (e.g., T50 = 331 °C and SmCO2 = 95.3%). The occurrence of structural and synergistic effects among the K, Mn, and Ce atoms in the catalysts was favorable for enhancing their catalytic activity towards the combustion of diesel soot. Furthermore, the temperatures required for the complete combustion of the soot (<400 °C) were well within the exhaust temperature range (175–400 °C), which means that the accumulated soot can be removed under the conditions of the diesel exhaust gas. These catalysts could therefore be used in numerous practical applications because they are easy to synthesize, exhibit high catalytic activity, and can be made from low cost materials.