Investigation On Interface Modulation And Catalytic Performance In CO Oxidation Of Copper-base Catalysts

Air pollution is one kind of environmental pollution,which has seriously threatened people’s daily life and physical health.It is urgent to develop new,cheap,efficient and stable catalysts to reduce environmental pollution.Among the many components of atmospheric pollution,reduction of CO has been a research hotspot in recent years.Mesoporous materials have high specific surface area and rich pores,which are important source of catalyst supports.CeO2 is also widely used as a catalyst additive due to its good ability to store and release oxygen.Based on CuCe-based catalysts,the influence of different SiO2 supports is studied in detail in this thesis.The effect of CeO2 as an additive and the calcination temperature in CuCe/Si catalyst are discussed deeply.Besides,different precursors were used to prepare CuCe catalysts.The details about our research as follows:1.A series of CuCe/Si catalysts were prepared by solid state impregnation with different silicon supports:silica,SBA-15 and MCM-41.The result of CO oxidation revealed that CuCe/silica had the best performance.XPS and TEM showed that the concentration of CeO2 and CuO on the catalyst surface is higher in CuCe/silica than those in other two catalysts.Also,the XPS result revealed that CuCe/silica had much more oxygen vacancies and Ce(Ⅲ).From the results of H2-TPR and in situ DRIFT,we could conclude that CuO was dispersed on both SiO2 and CeO2.In CuCe/silica,more CuO was dispersed on CeO2,which produced more Cu-Ce interface and improved catalyst performance.2.Solid state impregnation was used to prepare Cu/SBA-15 catalysts.After that,CeO2 was introduced in the catalysts.Large particles of crystalline CuO were detected by XRD、TEM、H2-TPR.After CeO2 was introduced,the crystalline CuO was no longer detected when the calcination temperature of Cu/CeO2-SBA-15 exceeded the Tammann temperature of CuO.We suggested that the crystalline CuO flew and shifted on CeO2.Much more Ce(Ⅲ)was detected by XPS after introduction of CeO2,which produced many oxygen vacancies and more Cu+.The infrared spectrum showed that more Si-OH could be detected in CuCe/SBA-15because the Cu dispersed on SiO2 flew to combine with CeO2(Si-O-Cu changed to Si-OH).3.The 01CuN and 01CuA catalysts were prepared by wet impregnation method.Different precursors(copper nitrate and copper acetate)were used.CeO2 was supporter.The differences of catalysts caused by different copper precursors were investigated.H2-TPR revealed that the catalyst prepared by copper acetate had better redox performance.Much more Cu+ was obtained in 01CuA according to CO-TPD and XPS results.