Catalytic Oxidation Of Diesel Soot Over Transition Metal Doped Lanthanum Stannate Pyrochlores With A O2/No Mixture

In order to solve the soot emission problems from diesel engines, a series of La2Sn1.8M0.2O7 (M= Sn, Mn, Fe, Co, Cu) oxides with pyrochlore structure were synthesized by co-precipitation, and investigated for soot oxidation with a O2/NO mixture by Temperature-programmed Oxidation. The incorporation of transition metals strongly influences the crystallite size, surface area and redox properties of the catalysts. All the pyrochlore oxides display catalytic soot oxidation activity with nearly 100% selectivity towards CO2. The doped pyrochlores exhibit higher activities than the undoped, which may be related to the enhancement of reducibility. Among them, La2Sn1.8Mn0.2O7 possessed the best activity with Ti = 341 °C. The pyrochlore oxides seem to be a novel active alternative for catalytic soot oxidation.