Effect of A-site substitution on the simultaneous catalytic removal of NOx and soot by LaMnO3 perovskites

The simultaneous catalytic removal of NOx and soot by La1−xMxMnO3 (M = K, Sr, Pr; x = 0, 0.1, 0.2, 0.3) perovskites was investigated. The properties of the catalysts were characterized by XRD, FT-IR, BET, SEM, XPS, H2-TPR and soot-TPR. The results showed that K+, Sr2+ and Pr3+ successfully entered the lattice and formed a perovskite structure. The catalyst doped with K+ exhibited the most outstanding performance. The La0.8K0.2MnO3 catalyst showed the best catalytic activity with 39.07% NO conversion and 92.41% N2 selectivity; the soot burning rates reached 10% (Ti) and 50% (Tm) at 365 °C and 420 °C, respectively. More oxygen vacancies and Mn4+ ions appeared in the catalyst with the increase in K+, due to which the ratio of Oads/Olat and Mn4+/Mn3+ changed regularly; this increased the ability of removing NOx and diesel soot particles.