Facile synthesis of three-dimensional ordered macroporous Sr_1-xK_xTiO₃ perovskites with enhanced catalytic activity for soot combustion

Three-dimensionally ordered macroporous (3DOM) perovskite catalysts possessing sufficient contact points are conducive to improving the catalytic combustion of soot. In this work, 3DOM Sr_1-xK_xTiO₃ (x = 0, 0.1, 0.2, and 0.3) perovskite-type catalysts were prepared through a colloidal crystal templating method. The as-prepared samples were analyzed by FESEM, TEM, XRD, FT-IR, N₂ adsorption-desorption, H₂-TPR, XPS, O₂-TPD and XRF techniques as well as simulated soot combustion reactions afterwards, to investigate the morphologies, physicochemical properties and catalytic activity performance. Titanium sol can convert to TiO₂ at a relatively low temperature and stabilize the 3DOM structure, which is beneficial for restraining the destruction of the 3DOM skeleton after potassium is introduced. On the one hand, the presence of potassium can form more oxygen vacancies, which may facilitate the generation of active oxygen species and accelerate soot combustion. On the other hand, eutectic compounds come into existence, promoting the contact between the soot and catalyst. Nevertheless, too much potassium will to some extent destroy the macroporous skeleton. Comprehensively considering the intrinsic properties and structural integrity, the 3DOM Sr_0.8K_0.2TiO₃ perovskite catalyst shows the best catalytic activity for soot combustion with T₅₀ at 382 °C.