Study On Performance Of Modified Perovskite Catalyst For Styrene Catalytic Combustion

Volatile Organic Compounds?VOCs?are one of the most common air pollutants in China,and they are important participators in the formation of secondary pollutants such as ozone and PM2.5.The treatment of VOCs has attracted great attention in China.Catalytic combustion method has attracted wide attention due to its advantages of low combustion temperature,high purification efficiency and no secondary pollutants.In catalytic combustion processes,the choice of catalyst is critical.In this paper,modified perovskite catalysts La_1-xCe_xMnO₃?x=0,0.1,0.2,0.3,0.4,0.5?,LaMn_1-yCu_yO₃?y=0,0.1,0.2,0.3,0.4,0.5?and La_0.9Ce_0.1Mn_0.6Cu_0.4O₃ were prepared by sol-gel method.The catalytic combustion properties of these catalysts for styrene were investigated.The changes of physicochemical properties of these catalysts were studied by XRD,BET,ESEM,XPS,H₂-TPR and O₂-TPD.When Ce is doped at A site of LaMnO₃ perovskite catalyst,Ce doping can not exceed0.1 in order to form perovskite catalyst with complete crystal structure and high crystallinity.Ce doping in LaMnO₃ catalyst can improve the specific surface area,low temperature redox performance,Mn⁴⁺content,surface oxygen adsorption and lattice oxygen content,performance of catalytic combustion of styrene.When x=0.1,the performance of catalytic combustion of styrene is the best.T₅₀ and T₉₀ are 303?and 321?,respectively.When Cu is doped at B site of LaMnO₃ perovskite catalyst,the type of crystal structure of the catalyst will change and the specific surface area of the catalyst will decrease.With the increase of Cu doping,the Mn⁴⁺/Mn³⁺value of the catalyst increases gradually,low temperature redox performance is gradually enhanced,the content of lattice oxygen and the temperature of its desorption peak gradually increase.Doping Cu in LaMnO₃ catalyst can improve the catalytic combustion performance of styrene.When y=0.4,the catalytic combustion efficiency of styrene is the highest.T₅₀0 and T₉₀0 are 290?and 308?,respectively.When LaMnO₃ perovskite catalyst is doped with 0.1 Ce and 0.4 Cu at A and B sites respectively,the catalyst has rhombohedral crystal structure and produces trace impurities of CeO₂ and CuO.Compared with La_0.9Ce_0.1MnO₃ and LaMn_0.6Cu_0.4O₃ catalyst,La_0.9Ce_0.1Mn_0.6Cu_0.4O₃ catalyst has higher Mn⁴⁺/Mn³⁺value,better low temperature redox performance and abundant surface oxygen adsorption.The catalytic combustion efficiency of styrene is the highest,T₅₀0 and T₉₀ are 288?and 306?,respectively.