Researches Of Activity For NO Catalytic Oxidation Over Cu, Ce And Mn Based Catalysts

Recently, Selective catalytic oxidation of NO (SCO) with the method of absorption by liquid attracts more and more attention in the flue gas denitration process. Catalysts for NO oxidation are the keys which could restrict their industrial application. The activity of catalysts with single active component could not reach the goal, which could be found in nowadays researches. Active components mixed with each others were researched in this work. Cu, Ce and Ti based catalyst was prepared and found that the activity for NO oxidation increased obviously by this catalyst. Mn was also added in this work, which could improve the catalytic oxidation activity of catalysts at low temperature.The method of equivalent-volume impregnation was used for the preparation of catalysts. Fixed-bed reactor was used for testing catalytic activity of catalysts, and analysed the influence of catalysts activity by the mole ratio of Cu/Ce and adding Mn. Experiment also investigated the influence of catalysts activity by the temperature of calcination. SEM, XRD and XPS were used for researching the surface structure of catalysts, the degree of crystallinity and valence state of element. The kinetics of NO catalytic oxidation reactions over CuCeOx/TiO2and MnCuCeOx/TiO2were researched in this work.The experiment found that the CuCeOx/TiO2catalyst with mole ratio of Cu:Ce=l:2perform the best catalytic activity than any other CuCeOx/TiO2catalysts. But this catalyst could not have a good activity at low temperature of reaction. So Mn was added into CuCeOx/TiO2catalyst, and the constituted MnCuCeOx/TiO2catalyst could perform a certain catalytic activity for NO oxidation.The experiment has studied on the effect of calcination temperature to catalysts and found that350℃and450℃are the best calcination temperature for CuCeOx/TiO2catalyst and MnCuCeOx/TiO2catalyst respectively. CuCeOx/TiO2catalysts under high calcination temperature with the serious phenomenon of adhesion and crosslinking could be found from the analysis of characterization. The surface with bedded structure changed into adhesion and crosslinking for MnCuCeOx/TiO2catalysts at high calcination temperature. Oxygen of activated absorption increased obviously for catalysts with Mn. When inlet concentration of NO was500ppm, O210%and space velocity24000h1, oxidation extent of NO over CuCeOx/TiO2reached0.64at350℃. The same condition of MnCuCeOx/TiO2, oxidation extent of over MnCuCeOx/TiO2reached0.55at250℃,0.76at300℃, and0.69at350℃for the effect of thermodynamic equilibrium.The kinetics of NO catalytic oxidation reactions over CuCeOx/TiO2and MnCuCeOx/TiO2were researched in this work, and gained the activation energy of these two reactions. It is found that the activation energy of CuCeOx/TiO2catalyst is higher than MnCuCeOx/TiO2catalyst, which could judge that the activity of MnCuCeOx/TiO2catalyst is better than CuCeOx/TiO2catalyst.