Abstract: La0.8K0.2MnO3 and La0.8K0.2CuxMn1-xO3 was prepared by partial substitution of K for La in LaMnO3 and further partial substitution of Cu for Mn, respectively. The catalytic properties of the two catalysts for simultaneous removal of NOx and soot were evaluated through the temperature-programmed reaction technique. X-ray photoelectron spectroscopy (XPS) was adopted to investigate the effect of partial substitution from the aspect of the catalyst composition. The X-ray diffraction results showed that the two kinds of substitution promoted the formation of perovskite. To maintain the electroneutrality, Mn2+ turned to Mn3+ and even some Mn4+ after the partial substitution of K for La, which greatly improved both the activity and the selectivity of the catalysts. The partial substitution of Cu for Mn further promoted the transition of Mn3+ to Mn4+, which deactivated the catalysts a little but improved the selectivity of the catalysts again owing to the synergistic effects of Cu2+ and Mn3+. The XPS results indicated that surface Mn3+ and Cu2+ were the effective ions for the simultaneously catalytic removal of NOx and soot.

Key words: perovskite, potassium, copper, X-ray photoelectron spectroscopy, nitrogen oxide, soot