| VOCs is one of the main sources of air pollution. The progressive increase of VOCs emissions, the information of their hazardous nature, and the resulting increasingly more restrictive environmental regulations in the industrialized countries, have induced the development of different methods for the elimination of VOCs in the last few decades. Among them, incineration is a convenient way to convert VOCs into nontoxic carbon dioxide and water. However, conventional thermal incineration requires an oprating temperature as high as 1000℃, and consumes significant amounts of energy. On the other hand, catalytic combustion can be conducted at much lower temperatures (approximately 300℃), and the selectivity of the catalytic reaction could be effectively controlled. It has the advantages of providing nearly total elimination of pollutants, with no generation of organic by-products at moderate temperatures, hence low operation cost. Thus, catalytic combustion has been recognized as one of the promising techniques for VOCs abatement. Much attention should be paid to the improvement of catalyst activity that could prompt the complete oxidation at rather low temperature.In this paper, we studied the results of catalytic combustion toluene over the type of CuMn mixed oxides catalysts. Catalytic activity tests were performed in a continuous flow fixed-bed reactor and an on-line gas chromatography was used to analyze toluene concentrations in the feed and effluent gas.1) In the originally work, CuMn/TiO2 and CuMn/γ-Al2O3 were prepared by impregnation method; conventional CuMn mixed oxides were prepared by co-precipitation; Nanometer particle of CuMn mixed oxides were prepared in reverse microemulsions. Experiment of activity appraisal suggested that CuMn type catalysts have good activity on toluene, and the activity of CuMn/TiO2 and Nanometer particle of CuMn mixed oxides were better than CuMn/γ-Al2O3 and conventional CuMn mixed oxides. Considering the economical and practical purpose, CuMn/TiO2 was chosed to give deep study.2) CuMn/TiO2 catalysts was prepared by impregnation method and applied for total oxidation of toluene. Effects of CuMn mixed oxides loading, [Cu]/ [Mn] ratio and calcined temperature on toluene conversions were investigated. We found that the new type of TiO2-supported CuMn mixed oxides catalysts are much more active than those conventional catalysts such as: Cu/TiO2,Mn/TiO2,CuMn/γ-Al2O3 and CuMn mixed oxides etc. CuMn/TiO2, in particular, could catalyze the complete oxidation of toluene at a temperature as low as 220℃which is 30℃lower than that of CuMn/γ-Al2O3.The effect of the nature of the support on the catalytic activity was notable. The catalysts have been characterized by X-ray diffraction (XRD) techniques, N2 adsorption /desorption and Temperature programmed reduction (TPR). The XRD analysis revealed that the major active material of CuMn/TiO2 is CuMn2O4 which could improve the activity of CuMn/TiO2 excellently. The TPR-profile of CuMn/TiO2 shows a reduction process that is shifted to lower temperature for all the oxide componenets. The surface specific area of TiO2 is 45.34 m2/ g, which can induce the CuMn mixed oxides particles existing as a desirable value. And such a desirable value can weaken the metal-support interaction becomingly in our catalyst. All these results suggest that CuMn/TiO2 catalyst has the best redox property, which must be one of reasons for highest activity for the catalytic oxidation of toluene.CuMn/TiO2 catalyst showed an excellent stability of the catalytic performance during a long-term stability test of 48h.3) The blank TiO2 support was also found to exhibit certain activity for toluene oxidation, although its T50 is rather higher (300℃). However, the blankγ-Al2O3 exhibits no activity for toluene oxidation. Synergetic effect of CuMn and TiO2 also more promoted the catalytic activity of catalysts.4) This work was carried on the condition of our laboratory. The molding experiment of CuMn/TiO2 showed that in the way prepared CuMn/TiO2 powder at first then molding the catalysts with 2.70ml/10g dry catalysts powder in the particle diameter of 48~100μm, reached 95% toluene conversion when the react temperature is 260℃, and with strong mechanical intensity, has been rather suitable for the industry application.
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