| With the development of global traffic system,especially,the design and application of engines in lean - burn condition, a great deal of NOX from automotive exhaust not only affect badly on the environment ,but also threat the health of human. Effective removal of NO by catalytic process has attracted extensive attentions.So the rese- arch of de-NOX catalysis for automotive exhaust control has become a popular subject. Direct decomposition would in principle be the most efficient and the least expensive solution to their abatement.As catalyst for NO removal,perovskite-type oxides have attracted particularly attentions because of their stable structure and unique physical and chemical properties.In this dissertation, a series of perovskite - type oxides via substituting the A or B site of La(Sr)FeO3 were successfully synthesized through citric acid complexing sol- gel method. The presented samples were characterized by thermogravimetric -differential thermal analysis(TG-DTA),infrared spectra (IR), X-ray diffraction(XRD), H2 temperature programmed reduction(H2-TPR)and N2 adsorption. The influence of doping elements in A site and B site and the doping ratio on the catalytic activity of perovskite-type oxides was also respectively discussed in this thesis.The catalysts were characterized by thermogravimetric -differential thermal analysis(TG-DTA). The experimental results showed that the oxides calcinated at 800℃possessed the characteristic perovskite structure. X-ray diffraction verified the oxide materials have obvious characteristic diffraction peaks, less mixed peaks, perfect crystalline phase and nano-sized.IR results showed the substitution of Sr at La site of LaFeO3 increased the activity of B-O and thus resulted in the improvement of decomposing NO to N2. H2-TPRdemonstrated that the nature of transition metals at Bsite for NO decomposition play an important role in the catalysis for NO decomposition over perovskite-type oxides. |
PDF Full Text Request