The Study Of Catalytic Combustion For Chlorinated Volatile Organic Compounds Over Vanadium-based Catalysts

Chlorinated Volatile Organic Compounds?CVOCs?are usually generated from a wide range of industrial processes,including machinery,petrochemical,pharmacy and paint.Those compounds have a great hazards on the environment and public health.Among the various CVOCs abatement treatments,catalytic oxidation is a promising method because of its low energy consumption,high efficiency,easy industrial application and its conversion of CVOCs into harmless substances,without dioxins formation since it can operate at low temperature.A series of Vanadium-based bimetallic catalysts were prepared by impregnation method,Chlorobenzene?CB?and Dichloromethane?DCM?were chosen as model compound of Chlorine Volatile Organic Compounds?CVOCs?to evaluate the catalytic activity.The physical-chemical properties of the catalysts were investiganed by XRD?BET?H2-TPR?NH3-TPD and Raman.?1?The V-M/TiO₂?M= Cu?Cr?Ce?Mn?Mo?catalysts were prepared by impregnation method.Catalytic activity of Chlorinated Volatile Organic Compounds?CVOCs?,such as chlorobenzene?CB?and Dichloromethane?DCM?over V-M/TiO₂ were investigated.It was found that the V-Mo/TiO₂ catalyst could completely combustion oxidation of chlorobenzene into CO₂ and HCl at 260?,which was related to the biggest BET surface and highly dispersed of surface acidity;Moreover,the V-Mn/TiO₂ catalyst showed a high activity and good selectivity for catalytic oxidation of dichloromethane?DCM?,with a 100%conversion obtained at 380?.This performance was attributed to a large amount of active surface oxygen,which could enhance the ability of deep oxidation of dichloromethane.While the doping of Cr and Cu into V2O5/TiO₂ catalysts lead to numerous loss of BET surface and acdity.The reduction performance of catalysts falled off and there were large quantity of CrO3 and V2O5 crystalline phases gathered on catalysts surface.These changes decreased the catalytic activity when catalytic combustion of CB and DCM.?2?A series of Vanadium-Nickel oxides catalysts supported on titania for Dichloromethane?DCM?catalytic combustion were prepared by impregnation method,the effect of DCM concentration and GHSV were also examined.The results showed that the 3 V-7Ni/Ti02 sample exhibited the best catalytic activity for DCM oxidation since a total conversion was reached at 300?.The maximum CO₂ and HCl yields were 95%and 90%and without formation other harmful organic compounds such as CHCl3,CH2O.No obvious decrease in the catalyst performance was seen during the 24 hours test.DCM first reacted with surface OH groups of the catalysts to detach the chlorine atoms,then breakage the hydrogen under the effect of NiO.The interaction between NiO-VOx and Ti02 promoted the adsorption and dehydrochlorination of DCM due to the presence of Br???nsted sites.Moreover,the synergy between NiO and VOx improved the mobility of active oxygen species,that was benefit for the deeper degradation of the intermediates produced in the destruction process of DCM.