Three-dimensionally ordered macroporous LaCoxFe1−xO3 perovskite-type complex oxide catalysts for diesel soot combustion

Polymethyl methacrylate (PMMA) microspheres with diameters of 300–500 nm were prepared by using a modified emulsifier-free emulsion polymerization technique with water–oil biphase double initiators. A series of three-dimensionally ordered macroporous (3DOM) LaCoxFe1−xO3 (x = 0–0.5) perovskite-type catalysts were synthesized by using colloid crystal template (CCT) method with the PMMA microspheres as template. The microspheres and 3DOM catalysts were characterized by means of XRD, FT-IR, SEM and Laser particle size analyzer, and the catalytic performances of the catalysts for diesel soot combustion were investigated by temperature-programmed oxidation (TPO) reaction. The results indicated that the obtained PMMA microspheres did not aggregate and their solid content (i.e., the mass percentage of polymer microspheres in the whole emulsion polymer) reached 9%. Their size distribution was narrow and the microspheres with different sizes can be designed under different conditions. Except LaCo0.7Fe0.3O3, all the catalysts formed 3DOM structure and possessed a hexagonally well-ordered array. Their macroporous diameters were in the range of 250–300 nm. The 3DOM catalysts had better catalytic performances than the nonmacroporous particle catalysts for diesel soot combustion. Among the studied catalysts, the 3DOM LaCo0.5Fe0.5O3 catalyst had the highest catalytic activity, and its T50 and image were 397 °C and 99.7%, respectively.