Preparation Of Multistage Aperture Composite Mn/TiO₂ Catalyst And Their Catalytic Properties For Chlorobenzene Combustion

With the development of national economy,environmental pollution has increasingly attracted extensive attention of the whole society.Dioxin,which is carcinogenic?teratogenic and reproductive toxicity,has a great impact on human society and the natural environment.In this paper,the performance of the catalyst structure and function which impacted by the multi-stage composite metal catalyst structure and other factors has been discussed.The research subject is supported composite metal oxide catalyst while the Chlorobenzene is used as a model of chlorinated aromatics.The specific work has been done as following:1.Core-shell Mn/TiO₂ mixed oxide catalysts?Mn/Ti-cs?were prepared by incipient-wetness impregnation method.The obtained catalysts were characterized by a series of means.It was found that multistage aperture composite Mn/TiO₂ catalyst possesses high activity for catalytic combustion of CB.Among these,Mn/Ti20-cs showed the best activity,the conversion of chlorobenzene was 90% when the temperature was 296 °C,which was higher than the compared Mn/TiO₂ nanoparticles with the same Mn/Ti mass ratio?Mn/Ti20-np?.We found that the porous structure and special morphology are the main factors to increase the catalytic activity,which was beneficial to the diffusion and degradation of CB molecule and other intermediate products.2.A series of metal-loaded mesoporous silica catalysts,M/KIT-6?M=Mn,Cu,Fe,Cr,Sn?,were prepared by incipient-wetness impregnation method.The effects of metal oxide species and concentration on the textural structure and catalytic properties3.werestudied in detail.Mn/KIT-6 catalysts having different molar ratios of Mn/Si were found to possess high catalytic activity forcatalytic combustion of CB.Among these,Mn3/KIT-6 was the most active catalyst,for which the complete combustion temperature?T90?of chlorobenzene was 210.7 °C.It was found that thedispersion,specific surface area and reducibility are the main factors influencing the catalytic activity.By increasing the Mn/Si molar ratio to 1/2,T90 was raised to 238.5 °C.This is due to the decrease of pore volume and specific surface area caused by increase in the amount of Mn in the channels of KIT-6,increased agglomeration of Mn,and the lowering of Oads/?Olatt+Oads+Owat?concentration ratio.