| Chlorobenzene is one of the important components of volatile organic pollutants.As an important chlorobenzene degradation technology,catalytic oxidation degradation of chlorobenzene is facing the challenge of developing efficient and stable environment-friendly catalysts.In order to improve the low-temperature catalytic activity of manganese cerium composite oxide catalysts for the oxidation of chlorobenzene,γ-Al2O3 with large specific surface area and different acidic centers and CNTs with tubular structure are doped to synthesize composite support γ-Al2O3-CNTs,and MnOx-CeO2/γ-Al2O3-O-CNTs catalysts are prepared.The catalysts are characterized by BET,XRD,FTIR and NH3-TPD.The effects of catalyst carrier,the amount of loading,the concentration of chlorobenzene and the space velocity on the catalytic oxidation degradation of chlorobenzene are investigated.In order to determine the suitable ratio of manganese cerium for preparing supported manganese cerium catalysts,manganese cerium composite catalysts with different ratios of manganese cerium were prepared,and the catalytic oxidation activity of chlorobenzene is investigated.The results show that when the molar ratio of Mn/Mn+Ce is 0.86,the conversion of chlorobenzene can reach 50%under 145 ℃.When the reaction temperature is 195～345℃,the conversion of chlorobenzene can reach 67.9%,which is higher than that of other catalysts.A series of composite carriers,γ-Al2O3-CNTs,are prepared by sol-gel method.MnOX-CeO2/γ-Al2O3-CNTs catalysts with different manganese cerium oxides were prepared by isometric impregnation method.The results show that under the conditions of a space velocity of 22000 h-1 and an initial concentration of chlorobenzene of 500 ppm,the conversion rate of 10%MnOx-CeO2/γ-Al2O3-CNTs catalyst to chlorobenzene is higher than that of MnOx-CeO2/γ-Al2O3 catalyst and MnOx-CeO2/CNTs catalyst,but the highest conversion rate is only 37.1%.The 10%MnOx-C eO2/γ-Al2O3-O-CNTs catalyst prepared by introducing C=O and-C-O partial acidic functional groups into CNTs by mixed acid acidification has a chlorobenzene conversion rate of 65.6%at 195℃.The conversion of chlorobenzene over 20%MnOx-CeO2/γ-Al2O3-O-CNTs catalyst can reach 91.1%at 345℃,which is significantly higher than the MnOx-C eO2 catalyst.The space velocity is 11000 h-1,20%MnOx-C eO2/γ-Al2O3-O-CNTs can completely convert chlorobenzene at 345℃,the degradation rate of the catalyst to chlorobenzene is always 100%.There is a strong correlation between the surface acidity of catalyst and its activity.NH3-TPD results show that the 20%MnOx-CeO2/γ-Al2O3-O-CNTs catalyst has obvious detection peaks at 150～250℃ and 300～400℃ respectively,and the surface acidity is strong,which is helpful for further oxidation of dechlorination intermediates and desorption of chlorinated products.In addition,the acidic functional groups on the surface of the catalyst can combine with the aromatic rings in chlorobenzene and play a strong coordination role,which is conducive to the degradation of chlorobenzene. |
