Preparation And Catalytic Oxidation Of Esters Over ZSM-5 Zeolite Supported Manganese-based Composite Oxides Catalyst

Recently,high activity and low cost non-noble metal oxides catalysts have been extensively researched for catalytic oxidation of VOCs.In the present thesis,a series of H type ZSM-5 zeolite supported manganese-based oxides catalysts had been synthesized by a redox-precipitation mothod.The catalytic combustion of ethyl acetate and butyl acetate was selected as probe reaction,screening optimal preparation?Cu/Mn ration,calcination temperature,catalyst loading,doped cerium?and reaction?space velocity,VOCs concentration?conditions.The catalysts were characterized by XRD,BET,SEM,H₂-TPR,XPS,EDS,etc.The main conclusions are as follows:1)The results showed that catalyst with Cu/Mn=1:2,20%loading,calcined at 500°C exhibited the best catalytic activity towards ethyl acetate,the combustion temperature was300°C.When the Cu/Mn ratio was 1:2,the activity of catalyst was promoted due to the violent interaction between Cu and Mn,resulting in the emergence of new highly dispersed active centers,more oxygen vacancies and active oxygen species;when calcination temperature was 500°C,the catalyst has great grain growth on the surface and higher calcinations temperature may lead to the aggregation.When the catalyst loading was 20%,the surface active components are dispersed more uniformly.2)The Cu₁Mn₂Ce_0.5/HZSM-5 catalyst?Mn/Ce=1:0.25,Ce doped?showed an excellent catalytic oxidation activity of ethyl acetate at 280°C.The maximum conversion rate was 97.7%.When the Mn/Ce ratio was 1:0.25,Cu and Mn ions entered into the CeO₂lattice with a slightly larger ionic radius to form a CuMnCeO solid solution,which was highly dispersed on the surface,reduced the H₂ reduction peak,and improved the capacity of active oxygen transfer.3)Effects of space velocity and VOCs concentration examined for the catalytic combustion of ethyl acetate and butyl acetate on Cu₁Mn₂Ce_0.5/HZSM-5.It was shown that the catalyst activity decreases as the space velocity and VOCs concentration increases.In a certain range,the variation of space velocity has greater influence on catalytic activity than VOCs concentration.The highest removal rate of butyl acetate was 95.6%.4)The effect of Cu₁Mn₂Ce_0.5/HZSM-5 catalyst on catalytic activity for 80h had shown that the catalytic activity of the catalyst can be maintained above 90%in the atmosphere of ethyl acetate and butyl acetate,which has great stability.