Degradation Of Trichloroethylene By Catalytic Ozonation

Volatile organic compounds?VOCs?have a wide range of sources,VOCs are harmful to the environment and the human body,and chlorinated volatile organic compounds?CVOCs?have three adverse effects.After entering environment,CVOCs will cause enduring harm to human beings.Trichloroethylene,as a typical representative of CVOCs,is widely used in industrial production as an organic solvent.It is imperative to find effective methods for trichloroethylene degradation.Trichloroethylene can be degraded into H2O,CO₂ and HC1 by catalytic ozonation,which has the characteristics of low cost and no secondary pollution,and the key lies in how to choose the catalyst.The catalytic activity of the noble metal catalyst is high but the price is expensive.The cost of the transition metal catalyst is low,the efficiency is low and the life needs to be improved.This paper aims to screen the composite transition metal catalyst with good catalytic performance and longer life.In this paper,catalysts were prepared by impregnation method,and supported on ?-Al2O3,supported by ferromanganese,manganese-lanthanum and manganese-copper,adding cerium and different loads,under the condition of the concentration of trichloroethylene is 200 mg/m3,the concentration of ozone is 700 ppm and the feed velocity is 5000/h,the effects of the different active components on the catalytic activity are investigated.The results showed that the catalyst had the highest catalytic activity when 3%Mn,0.6%Cu and 0.5%Ce were loaded,and the catalysts were characterized by XRD,XPS and SEM-EDS.The effect of humidity on the reaction was investigated.The results showed that the increase of relative humidity could reduce the catalytic efficiency and O3 decomposition rate of the catalyst,and to a certain extent increased the selectivity of CO₂,the reason is the presence of water inhibited the contact between the surface active site of the catalyst and the O3.The deactivated catalyst was calcined at 425 ? for 1h.The activated catalyst improved the catalytic efficiency and the O3 decomposition rate to a certain extent,but the selectivity of CO₂ could not be significantly improved.Based on the above results and the determination of IR and determination of Cl,it is presumed that the products of reaction are mainly two chloroacetic chloride,CO₂,HCl,and so on.