Effect of Mn Incorporation Into Nd2Sn2O7 Pyrochlore Oxides on Catalytic Oxidation of Soot Particulates

A series of Nd2Sn2-xMnxO7 (x = 0, 0.05, 0.10, 0.20, 0.30, 0.40) pyrochlore catalysts were prepared by co-precipitation and calcinations method. The as-synthesized products were characterized by XRD, FT-IR, H-2-TPR, N-2 Adsorption-Desorption, DLS and PL techniques. Their catalytic activity for soot oxidation was investigated by TPO technique under both O-2 and NO+O-2 atmosphere. The incorporation of Mn strongly influences the textural properties, Sn-O bond strength, surface oxygen vacancy and redox properties of the catalysts, resulting in different catalytic performance of soot oxidation. All proychlore catalysts display soot oxidation activity with above 70% selectivity towards CO2 formation. The Mn doped solids exhibit higher activities than the undoped one in O-2, which may be related to the enhancement of reducibility and the increased surface oxygen vacancies. The presence of NO in the gas phase significantly enhanced the soot oxidation activity with ignition temperature decreased to about 350 degrees C, which is due to the promotion effect of NO2.