Synthesis, characterization and catalytic activity for NO–CO reaction of Pd–(La, Sr)2MnO4 system

LaxSr2−xMnO4 (0 ≤ x ≤ 0.8) oxides were synthesized and single-phase K2NiF4-type oxides were obtained in the range of 0.1 ≤ x < 0.5. The catalytic activity of LaxSr2−xMnO4 for NO–CO reaction increased with increasing x in the range of solubility limit of La. La0.5Sr1.5MnO4 showed the highest activity among LaxSr2−xMnO4 prepared in this study, but its activity was inferior to perovskite-type La0.5Sr0.5MnO3. Among the Pd-loaded catalysts, however, Pd/La0.8Sr1.2MnO4 showed the higher activity and the selectivity to N2 than Pd/La0.5Sr0.5MnO3 and Pd/γ-Al2O3. The excellent catalytic performance of Pd/La0.2Sr1.2MnO4 could be ascribable to the formation of SrPd3O4 which was detected by XRD in the catalyst but not in the other two catalysts.