| Because of the lower cost and analogous higher catalytic activity, the non-noble metal catalysts have been well studied, for volatile organic compounds (VOCs) purification in recent years. The Cu-Mn Complex Oxides catalysts are key representatives among them. In this study, the Cu-Mn Complex Oxides catalysts were prepared by hydrothermal homogeneous precipitation method with urea as precipitant. The catalytic performance on Cu-Mn complex oxides was investigated by catalytic combustion of toluene as the probe reaction. Based on the results of catalytic performance and characterization, the catalytic mechanism was studied. The research contents and results were as follows:(1) The effects of preparation conditions on Cu-Mn complex oxides catalysts’catalytic performance were studied, including Cu/Mn molar ratio, calcined temperature, hydrothermal temperature, hydrothermal time and urea amounts. And the effects of process conditions were studied too. It was favorable to generate Cu0.451Mn0.549O2crystal phase as the decrease of Cu/Mn molar ratio. The existence of too many impurity phases, including CuO and Mn2O3generated respectively as the proportion was too greater or too lower, was not favorable to the catalytic combustion of toluene. The main crystal phase of catalysts were MnC03after non-calcined or400℃calcined. Once the calcined temperature was higher than600℃, many Mn2O3phases would appear. The Cuo.451M0.549O2could be the catalysts’mainly phases only after500℃calcined. And they showed good catalytic performance. The main phases of catalysts were Cu0.451M0.549O2under the preparation conditions of hydrothermal temperature150℃and the hydrothermal time24h, which showed good catalytic performance. The best preparation conditions were:Cu/Mn molar ratio1:2, urea amounts0.16mol, hydrothermal temperature150℃, hydrothermal time24h, calcined temperature500℃.(2) The evaluation of catalytic performance was studied by catalytic combustion of toluene as the probe reaction. The catalyst composition, surface morphology, structure and performance were characterized by TG-DSC, BET, XRD, SEM, EDS, Raman, XPS, H2-TPR and O2-TPD. The results indicated that the CU0.451M0.549O2was the catalytic active center and the main contributor for the surface adsorbed oxygen and the bulk lattice oxygen. Cu0.451M0.549O2and small amount of CuO were synergism to improve the catalytic performance. The XPS results indicated that the surface species of the catalyst showed multi-valence state(3) The ignition temperature T10was at175℃and the complete conversion temperature T99was at210℃, which showed by the catalyst prepared under the best preparation condition. The variation of toluene concentration (0.5g/m3～12g/m3) and space velocity (6000h-1～40000h-1) had little effect on the catalytic combustion performance. The Cu-Mn complex oxides catalysts showed good performance under such variation. The complete conversion of catalyst had been over98%during the100h lifetime test. The valence of surface species and the surface morphology had little change before and after the lifetime test of catalyst, which illustrated that the Cu-Mn complex oxides catalysts showed high catalytic performance and stability.Prepared by impregnation-precipitation method, the CuxMnyOz/Ni nickel foam monolithic catalysts with copper manganese as active component were studied either in this thesis. The CuMn?Oz/Ni nickel foam monolithic catalyst which prepared under the condition of Cu/Mn molar ratio1:2, reaction time6h and calcined temperature400℃showed good performance for catalytic combustion of toluene. And the complete conversion temperature T99was lower to275℃, which provided a good reference for industrial application. This catalyst had small BET area and lower loading. The cube morphology complex oxides Cu-Mn-O-Ni loaded on the nickel foam skeleton may be the mainly active center of the catalyst. |
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