Study On The Preparation,Characterization And Catalytic Performance Of Mn-Modified CeO₂ Nanorod Catalysts For CO Oxidation

Carbon monoxide(CO),as a major air pollutant,is mainly emitted from the incomplete combustion of fossil fuels.At present,catalytic oxidation technology is the most effective technique to control CO pollution.However,commercial precious metal based catalysts have several disadvantages such as high prices,poor resistant to poisons,and limited resources.The development of highly efficient low-cost non-precious metal catalysts has become one of the current research hotspots.Mn-modified Ce O₂ nanorods(Ce O₂-NR)catalysts were prepared for CO catalytic oxidation.Coupled plasma spectroscopy(ICP),X-ray photoelectron spectroscopy(XPS)and other characterizations were used to study the structure-activity relationship between the microstructure of catalysts and catalytic activity.x Mn/Ce-NR{n_(Mn)/(n_(Mn)+n_(Ce))}=x%,x=1,2,5,8,10)composite oxides were prepared by hydrothermal method and impregnation method The catalyst is used for CO catalytic oxidation.The results show uniform nanorod with predominately exposed{100}crystal plane forms on Ce O₂ catalyst,and remains when loading Mn contents.BET results show that it has a larger specific surface area and pore volume;Compared with pure Ce O₂-NR,the catalytic activity is greatly improved after adding Mn.The 5Mn/Ce O₂-NR catalyst{Mn:(Mn+Ce)=0.05}exhibites better CO oxidation activity.The CO conversion of 5Mn/Ce O₂-NR catalyst exceeds 95%at 175?on 5Mn/Ce O₂-NR catalyst.However,in the presence of water vapor,the activity of the catalyst decreases significantly,and its stability needs to be further improved.A series of manganese-doped Mn_aCe_1-aO_x(a=0.01,0.02,0.05,0.08,0.10)nanorod composite oxides were prepared by one-step hydrothermal method,and their CO catalytic oxidation performances were investigated.The research shows that all Mn elements are successfully doped into the Ce O₂ lattice,and the catalytic activity increases with the increase of the Mn doping amount on the Mn_aCe_1-aO_x catalyst.The Mn_aCe_1-aO_x catalyst has a regular morphology,and the selective exposed surface is{100}crystal plane;Mn_0.05Ce_0.95O_x nanorods with high specific surface area(102.2 m~2/g),and small grain size(7.9 nm)are superior to undoped Ce O₂ in both catalytic activity and hydrothermal stability,the CO conversion at 175?exceeds 95%.The Mn_0.05Ce_0.95O catalyst after hydrothermal treatment has a complete CO conversion temperature at 175?,and a 100%conversation terperature at 185?,and shows good long-term stability.