Optimization of Catalytic Soot Oxidation by 3DOM Perovskite-Type La0.5-xKxSr0.5CoO3-δ Catalysts: Structural Insights and K Substitution.

Abstract

A series of 3DOM La_0.5-xK_xSr_0.5CoO_3-δ catalysts were synthesized using colloidal crystal templating and citric acid complexation methods. The substitution of K ions for A-site La ions was found to markedly enhance the catalysts' intrinsic activity, with the La_0.4K_0.1Sr_0.5CoO_3-δ catalyst showing exceptional performance comparable to commercial precious metal catalysts. The La_0.4K_0.1Sr_0.5CoO_3-δ catalyst demonstrated the highest catalytic activity, with T₁₀, T₅₀, and T₉₀ values of 280 °C, 335 °C, and 387 °C, respectively. The enhancement in intrinsic activity is primarily attributed to the electron-donating effect of K ions which maintains charge conservation and consequently increases the concentration of surface oxygen vacancies, leading to the formation of abundant active oxygen species. Additionally, the catalysts exhibited a highly ordered macroporous structure with interconnected pores, facilitating the diffusion of soot particles and enhancing contact efficiency with active sites. These findings not only advance the understanding of the structure-performance relationship in perovskite catalysts but also pave the way for the development of cost-effective catalysts for low-temperature soot abatement.