Preparation Of Composite Support Of Metal Oxide Catalyst And Investigation Of Its Catalytic Properties For The Selective Reduction Of NO

With the development of the Thermal Power Generation Technology and other industries as well as the increasement of the number of the automobile, the emission of nitrogen oxides is increasing. Meanwhile, in order to relieve the global energy crisis, the design and application of energy saving engines in lean-burn condition has been developing. Although it can save enery in lean-burn condition and enhance the burning efficiency of the fuels, it results in the largely increasing emission of NO. Not only does NO cause heavy environmental pollution, but also it do harm to people's health. Therefore, great importance is attached to the problem that how to remove NO effectively both at home and abroad.Selective catalytic reduction (SCR) of NO with hydrocarbon has become one of the important projects. To find out an efficient catalyst is of great importance for the research. Two kinds of catalysts with metal oxide composite support have been studied in this thesis:â‘ The composite support TiO₂-Al₂O₃ was prepared by coprecipitaition and modified with SO₄^2- followed by loading with Cu²⁺, then the CuO/ SO₄^2-/ TiO₂-Al₂O₃ was made.â‘¡The CeO₂-Al₂O₃ composite support was prepared by coprecipitation method with the mixed Al(NO₃)₃-Ce(NO₃)₃ aqueous solution dropping into the mixed NH4HCO3-NH3·H20 aqueous solution. The Cu/La/CeO₂-Al₂O₃ catalyst was prepared by the impregnation of CeO₂-Al₂O₃ with promoter La and active component Cu aqueous solution. Meanwhile, the structure and property of catalysts have been investigated by using the catalysts performances and the results of characterization.The investigation of the relationship between the catalytic activity and the structure of the Cu/SO₄^2-/TiO₂-Al₂O₃ catalyst indicated that the introduction of TiO₂ can significantly enhance the catalytic activity of the catalyst, especially at low temperature; using SO₄^2- to modify the TiO₂-Al₂O₃ composite support could obviously enhance the catalytic activity further more. The addition of SO₄^2- can lead to the result that SO₄^2- and Ti form the structure of superacid, accordingly improve the catalytic activity of Cu/SO₄^2-/ TiO₂-Al₂O₃ catalyst efficiently.The investigation of the relationship between the catalytic activity and the structure of the Cu/La/CeO₂-Al₂O₃ catalyst indicated that the CeO₂-Al₂O₃ could remarkably enlarge the catalyst surface area and pore size, increase the amount of Lewis acidity and enhance the reducibility, and the promoter La could further enlarge the catalyst surface area and pore size, increase the amount of Br(?)nzed acidity and the thermal stability. Consequently, the catalyst indicated the higher activity for the selective reduction of NO with propylene in excess oxygen. The NO conversion decreased slightly even at the presence of water vapor.