The Study Of Preparation,characterization And Performance For Catalytic Combustion Of Cu-Mn/γ-Al₂O₃ Catalysts

Cu-Mn/γ-Al₂O₃ catalysts has attracted a lot of attentions due to its advantages on catalytic combustion of volatile organic compounds（VOCs）,such as high performance at low temperature,high selectivity and low price.In this paper,Cu-Mn/γ-Al₂O₃ had been prepared by impregnation method and three factors（different calcination temperatures,different mole ratios of Cu/Mn and impregnation methods）were studied.The physicochemical properties of catalysts were characterized by XRD,TEM,BET,XPS and H₂-TPR.Their performances for catalytic combustion of toluene were evaluated in a fixed-bed tubular reactor.And the catalytic activity of catalysts was measured by the catalytic combustion of toluene.The stability of Cu-Mn/γ-Al₂O₃ catalyst was also discussed.The conclusions were drawn as follows:Firstly,effect of the calcination temperature of Cu-Mn/γ-Al₂O₃catalysts on catalytic activity was focused on phase composition of catalysts.At 550℃,the Cu-Mn/γ-Al₂O₃ catalyst showed higher activity because of the generation of new phase(Cu_1.4Mn_1.6O₄)and more Cu⁺and Mn⁴⁺ions present on the surface of the catalyst,with a lower reaction temperature(T₉₅5 was 286℃)and nearly 100%selectivity of CO₂.Secondly,it was synergistic effect between CuO and Cu_1.4Mn_1.6O₄ of catalysts prepared with different mole ratios of Cu/Mn that resulted in better performance.When prepared by 1:1 mole ratio of Cu/Mn,the catalyst showed better catalytic activity,with a lower reaction temperature(T₉₅5 was 305℃),which was 47℃lower than catalyst prepared by 1:0 mole ratio of Cu/Mn.Thirdly,the catalytic activity showed close connection with impregnation methods and content of Cu_1.4Mn_1.6O₄.The catalysts prepared by four-step impregnation method showed better catalytic activity and more Cu_1.4Mn_1.6O₄,with a lower reaction temperature(T₅₀was 262℃,T₉₅ was 280℃,respectively).Finally,the catalyst showed a good stablility for keeping 97%conversion of toluene for 10 h.