Study On Preparation Of Supported La_xCe_1-xMnO_n Catalysts For Catalytic Combustion Of Toluene

In this thesis,rare earth element La and Ce were used as the additives to promote the catalytic activity of Manganese based catalyst.Three different supported catalysts La_xCe_1-xMnO_n/?-Al₂O₃,La_xCe_1-xMnO_n/HY and La_xCe_1-xMnO_n/MOR were prepared and their catalytic activities were investigated in order to understand the influences of catalyst preparation method,content of the active component and structure of catalyst on the results of toluene removal.Experiment results indicated that the catalytic activities were greatly affected by the loading amount of the La_xCe_1-xMnO_n,the optimum loading amount for ?-Al₂O₃,HY and MOR were 12%,20% and 12% respectively.The BET results show that the surface areas,pore volume and sizes of the catalysts were decreased with the increasing addition of the metal component.Moreover,the surface area,pore volume and sizes of the catalysts were also decreased with the increasing calcination temperatures.The best calcination temperatures for all three kinds of catalysts was 450?,which indicated that the formation of stable metal oxide was only related with the calcination temperatures and independent with the structure of catalyst support.The catalytic activity was also affected by the ratio of La to Ce in the catalyst.The best ratio of La to Ce is 4:1 for all three kinds of catalystsXRD result indicted the metal oxide were evenly dispersed on the surface of the pore structure for all three kinds of catalysts.In addition,XRF result demonstrated that the loading capacity of catalyst for metal element was increased by the addition of La.Furthermore,the addition of La can also promote the thermal stability and physical strength of the catalyst.Different toluene inlet concentrations affect the catalytic combustion activities of the three kinds of catalysts in three different ways.In addition,high GHSV will result in the decrease in the toluene removal efficiency for all three kinds of catalysts,and it will be more pronounced for the La_xCe_1-xMnO_n/?-Al₂O₃ and La_xCe_1-xMnO_n/MOR catalyst.Moreover,increasing using time has little effect on the catalytic activity of La_xCe_1-xMnO_n/?-Al₂O₃ catalyst but has significantly influence the catalytic activity of La_xCe_1-xMnO_n/HY and La_xCe_1-xMnO_n/MOR catalyst.