The Studies Of The Catalysts For Simultaneous Removal NO_x And Soot

Diesel engines are attractive to various power devices and vehicles because of its leanoperation result in high fuel economy and good drivability. However, Diesel engine emissionshave led to serious environmental problems. There are two major pollutants: soot particlesand NO_xin diesel exhaust. They were inhaled to causing serious damage to lobectomy andlung, even to be carcinogenic. Under loose contact, ceria-manganese based oxides andperovskite were investigated as catalysts for the simultaneous removal NO_xand Soot in thiswork, considering the excellent redox properties of these oxides.A series of Mn-Ce mixed oxide catalysts were prepared for soot oxidation and eliminateNO_xby coprecipitation using of KMnO₄as precursor. The influence of molar ratios of Mn/Ceon the structure and property of the resulted materials was investigated in details. Thus, in thisstudy showed the series of catalysts not only have surface active oxygen but also have the Mnwith high oxidation state.Different loading of precious metals, alkali and alkaline earth-promoted metal wasloaded on Mn-Ce mixed oxide catalysts. It found that the catalytic activities of Mn-Ce mixedoxide catalysts can be improved by loading potassium. It was attributed to the meltingtemperature and decomposing temperature of KNO₃, which was useful to improve the contactstate between soot and catalyst. The Ba-loaded Mn-Ce mixed oxide catalysts were preparedthrough different preparation method or process. It was indicated that12wt%Ba/Mn₁Ce₃catalyst showed the best catalytic activity. The precious metals Pt was loaded on Mn-Cemixed oxide catalysts, it found that the activity of the loaded catalyst was reduced to Mn₁Ce₃catalyst due to the Cl-1, which is easy to make catalyst lost their active.Different perovskite oxide catalysts were prepared through the complex-combustionmethod. Compared with the precious metals, alkali or alkaline earth-promoted metal wasincoporated into A-sites of LaCoO₃, it was found that the potassium-substituted LaCoO₃（La1-xKxCoO₃） perovskite samples show much high activity for the soot oxidation. Otherwise,the incorporation of Fe into B-sites of perovskite oxides （La0.9K0.1Co1-xFexO₃） was found to bequite effective in enhancing the activity.