Preparation Of CuO-CeO₂ Oxides Supported On Glass-fiber Honeycomb For Catalytic Combustion Of Volatile Organic Compounds

Volatile organic compounds?VOCs?as one of the main atmospheric pollutants,has caused much attention.Catalytic combustion is one of the most interesting technologies for the destruction of emissions of VOCs due to its low cost,low energy requirement.However,transition metal oxide catalysts would be advantageous alternative to noble metals because of the commercial and technical advantages.We prepared the CuO-CeO₂ oxide catalyst supported on glass fiber honeycomb to research active component,calcined temperature,the molar ratio of Cu/?Cu+Ce?and additives on catalytic activity by catalytic combustion of VOCs.And also studied the relations between surface properties and activity by techniques such as BET,XRD,H2-TPR,NH3-TPD,VOCs-TPD.A series of CuO catalysts supported on glass fiber honeycomb were prepared by co-impregnation method with different active component?8%,10%,12%?and calcined temperature?500?,600?,700??respectively and their performance in the catalytic combustion of ethyl acetate was tested.The results have shown that Cu10/Al₂O₃-M-600 calcined at 600? showed the highest activity,the active component of which was 10%.CuO-CeO₂ monolithic catalysts with the molar ratio of Cu/?Cu+Ce??1,0.67,0.5,0.33,0.2,0?were prepared by co-impregnation method and their catalytic performance in the oxidation of ethyl acetate,isopropanol and toluene was evaluated.The addition of Ce can improve the catalytic activity.In the oxidation of ethyl acetate and isopropanol,Cu_0.5Ce_0.5/Al₂O₃-M showed the highest activity,100% conversion was achieved at 325?.Characterization data showed that copper oxide are highly dispersed on the catalyst,while CeO₂ appears with small nanoparticles,whose size increases with the decreasing of the molar ratio of Cu/?Cu+Ce?.Adding CeO₂ can decrease lattice oxygen species and the reducibility of catalysts,but evidently increases the amount of total acidity,especially the Lewis acid sites whichcaninfluence the adsorption of ethyl acetate and isopropanol.For Cu_0.5Ce_0.5/Al₂O₃-M,it can be seen that the conversion of ethyl acetate remains at about 97% during 50 h at temperature of 325?and GHSV of 20000h-1.This indicated that Cu_0.5Ce_0.5/Al₂O₃-M has excellent stability for the oxidation of ethyl acetate.The acid additives such as malic acid,citric acid,Lactic acid and the alkaline additives such as hexamethylenetetramine,triethylenetetramine,diethylenetriamine added to Cu_0.5Ce_0.5/Al₂O₃-M on the catalytic oxidation of ethyl acetate were investigated.The results show that adding additives cannot improve the catalytic activity.Adding acid additives can increase the amount of Br?nsted acid sites,but do not attribute to the Lewis acid sites and the adsorption capacity of ethyl acetate;adding alkaline additives improve the reducibility,but decrease the amount of total acidity,the Lewis acid sites and the adsorption capacity of ethyl acetate which synergically affects the catalytic activity.The total oxidation on CuxCe1-x/Al₂O₃-M catalysts takes place through Mars-van Krevelen mechanism,which means that reducibility and adsorption capacity of VOCs can synergically affect the activity of catalysts.