Influence of Calcination Temperature on the Dispersion Behavior and CO Oxidation Properties of CuO/γ-Al_2O_3 Catalyst

CuO/γ-Al_2O_3 samples were prepared by impregnatingγ-Al_2O_3 with an aqueous solution containing requisite amount of Cu(NO_3)_2.BET,XRD,UV-DRS,H_2-TPR and CO oxidation were employed to characterize the dispersion,reduction behavior and catalytic properties of CuO/γ-Al_2O_3 catalyst calcinated at different temperatures.The results indicate that the dispersion capacity of CuO on the surface ofγ-Al_2O_3 is about 0.56mmol/100m~2 when it is calcinated at 450℃;while for the samples calcinated at 750℃,Cu~(2+) would occupy both the octahedral and tetrahedral vacant sites on the (110) plane ofγ-Al_2O_3.For samples with low CuO loading amount,only the reduction peak of Cu~(2+) in octahedral coordination environment is observed in xxCu/Al-450 samples;while for xxCu/Al- 750 samples,the reduction peaks of Cu~(2+) in octahedral and tetrahedral coordination environment can be observed and the reduction of Cu~(2+) in octahedral coordination environment would promote the reduction of Cu~(2+) in tetrahedral coordination environment.The CO oxidation results indicate that the activity of dispersed CuO species in octahedral coordination environment is higher than that in tetrahedral coordination environment.