Three-dimensionally ordered macroporous SiO2-supported transition metal oxide catalysts: facile synthesis and high catalytic activity for diesel soot combustion

Abstract

Three-dimensionally ordered macroporous (3DOM) SiO₂ was synthesized by a colloidal crystal template (CCT) method, and 3DOM SiO₂-supported transition metal oxides catalysts were prepared by a facile incipient-wetness impregnation method. The as-prepared catalysts show well-defined three-dimensionally ordered macroporous structures. The transition metal oxides formed different sizes of nanoparticles and loaded onto 3DOM SiO₂. The as-prepared catalysts show high catalytic activities for soot combustion. Among the studied catalysts, the 3DOM MnO_x/SiO₂ catalyst (molar ratio of Mn to Si is 1 : 4) shows the highest catalytic activity among the studied catalysts, e.g. T₁₀, T₅₀ and T₉₀ are 297, 355 and 393 °C, respectively, and S^m_CO2 is 95.5%. The catalytic performances of 3DOM SiO₂-supported transition metal oxide catalysts are mainly controlled by three factors: the macroporous effects of the 3DOM structure, the redox properties of transition metal oxides and the sizes of transition metal oxide NPs. 3DOM SiO₂-supported transition metal oxide catalysts are promising for practical applications in soot combustion owing to high activity and low cost.