PMMA-templating preparation and catalytic activities of three-dimensional macroporous strontium ferrites with high surface areas for toluene combustion

Three-dimensional (3D) macroporous perovskite-type oxides SrFeO3−δ (i.e., SFO-xEG, x = 1, 3, and 6) with a cubic perovskite structure have been prepared using the citric acid-assisted poly(methyl methacrylate)-templating method in the presence of a certain amount (1, 3 or 6 mL) of ethylene glycol (EG). The physicochemical properties of the materials were characterized by means of numerous techniques and their catalytic activities were evaluated for toluene combustion. It is shown that the SFO-3EG sample possessed the best pore quality and highest surface area (ca. 34 m2/g). Most of the pores of SFO-xEG (x = 1, 3, and 6) were ca. 72, 52, and 64 nm, respectively. There was a good relationship of surface area, oxygen adspecies concentration, and low-temperature reducibility with catalytic performance of the sample (i.e., SFO-3EG > SFO-6EG > SFO-1EG > SFO-bulk). The SFO-3EG catalyst performed the best, giving a T50% of ca. 270 °C and a T90% of ca. 310 °C at space velocity = 5000 mL/(g h). It is concluded that the good catalytic performance of SFO-3EG was associated with its large surface area, high oxygen adspecies concentration, and good low-temperature reducibility as well as the high-quality 3D macroporous structure.