Catalytic performance of La_1-xRb_xMnO₃ perovskite in the simultaneous removal of NO and soot

A series of La_1-xRb_xMnO₃ perovskite catalysts (x=0, 0.1, 0.2, 0.3) were prepared by solvothermal method and characterized by means of XRD, FT-IR, SEM, XPS and H₂-TPR; their catalytic performance in the simultaneous removal of NO and soot was investigated in a fixed-bed micro-reactor. The results show that the La_1-xRb_xMnO₃ catalysts have a single perovskite structure and the Mn species exist in the form of Mn³⁺ and Mn⁴⁺. In comparison with LaMnO₃, when La³⁺ is partially substituted by Rb⁺, more high-valence Mn⁴⁺ and oxygen vacancies are formed in La_1-xRb_xMnO₃, which can improve the redox properties and enhance the catalytic performance of La_1-xRb_xMnO₃. With the increase of Rb⁺ content in La_1-xRb_xMnO₃, the conversion of NO increases and the soot combustion temperature decreases. For NO and soot removal over La_0.7Rb_0.3MnO₃, x=0.3, the peak CO₂ formation temperature (t_max) is 430 ℃, with a selectivity of 99.0% to CO₂; at 429 ℃, the maximum conversion of NO reaches 59.7%.