Effect of A-site element on the performance of three-dimensionally ordered macroporous manganese-based perovskite catalyst

Three-dimensionally ordered macroporous manganese-based perovskite catalyst (3DOM AMnO₃, A = Ce, La, Ni) were synthesized by PMMA hard-templating and impregnation method. Physicochemical properties of the samples were characterized by means of various techniques including XRD, BET, SEM, TEM, XPS and H₂-TPR, and their catalytic activities were evaluated by toluene combustion. It was found that the 3DOM AMnO₃ in each of the samples was perovskite in crystal structure, and only the samples possessed a good quality 3DOM architecture with a surface area of 48.8 m²/g. Due to the highest adsorbed oxygen species concentration (O_ads/O_latt = 2.330), the best low-temperature reducibility (The low-temperature reduction peaks of 3DOM CeMnO₃ catalysts occur at 425 °C) and the strong interaction between CeO₂ and MnO_x formed during calcination. The 3DOM CeMnO₃ sample showed lower apparent activation energy (34.51 kJ·mol^?1, SV = 15,000 h^?1) and the best catalytic activity for toluene combustion, with the reaction temperatures (T50%, and T90%) required for achieving toluene conversions of 50%, and 90% being 100 °C, 172 °C at SV = 15,000 h^?1, respectively.