Preparation And Property Research Of LaNiO_3+λ Rare-earth Perovskite Catalysts

With the development of the thermal power generation technology and other industries as well as the increasing of the number of the automobile, the emission of nitrogen oxides, carbon monoxide and hydrocarbon is increasing. The pollution not only effects on human life, but also directly hazards to human health; meanwhile, as the aggravation of the global energy crisis, the designation and application of energy-saving engines in lean-burn condition has been developing. Although it can improve combustion efficiency of the fuels in lean-burn condition, it results in the largely increasing emission of vehicle exhausts, especially for NO. Not only do NO, carbon monoxide and hydrocarbon cause series environmental pollution, but also they do harm to people's health. Therefore, much attention is paid to the problem that how to effectively purify automobile exhaust both at home and abroad. At present, noble metal has been used in three-way catalysts as active components for its good catalytic performance, but the precious metal is too expensive to popularization. So the research of the new type non-noble metal catalyst with high efficiency has become the top topic in recent years.A new type of nanometer perovskite composite oxide catalyst with high efficiency catalytic activity has been prepared and studied in this thesis: first of all, the LaNiO_3+λ was prepared by the sol-gel method, and then doped other metal ions in A bit to obtain La_0.8Cu_0.2NiO_3+λ and La_0.8Ba_0.2NiO_3+λ; Secondly, The La_0.8Cu_0.2Ni_0.8Mn_0.2O_3+λ and La_0.8Ba_0.2Ni_0.6Co_0.4O_3+λ were obtained by doped with other metal ions in B bit. The catalysts were characterized by means of the scanning electron microscopy (SEM), X-ray diffraction (XRD) and BET method.The investigation of the La_0.8Ba_0.2Ni_0.6Co_0.4O_3+λ catalyst indicated that the catalyst exhibited the high catalytic activity, and the light-off temperature of NO,CO and C3H6 were 300℃,198℃and 325℃, respectively; Ba and Co doping could increase the specific surface area and improve the three-way catalytic properties.The study of the relationship between the catalytic activity and the structure of the La_0.8Cu_0.2Ni_0.8Mn_0.2O_3+λ catalyst indicated that the addition of Cu can significantly enhance the reduction of NO, and Mn aubject to C3H6 transformation. Compared with La_0.8Cu_0.2NiO_3+λ, the light-off temperature and complete transformation temperature of C₃H₆ have reduced by 215℃and 180℃, and the maximum conversionof NO and CO were both up to 90 %. The results showed that La_0.8Cu_0.2Ni_0.8Mn_0.2O_3+λ had a perovskite structure, and the addtion of Cu and Mn could obviously refine the catalyst particles, increase the dispersion of active oxygen, enlarge the surface area, and improve the three-way catalytic properties.