Ce-Zr Based Composited Metal Oxides Prepared By SOL-GEL For Catalytic Degradation Of VOCs

Toxic and harmful volatile organic compounds(VOCs)in the atmosphere can cause great harm to the environment and human health.Catalytic oxidation is efficient and energy-saving among the VOCs control technologies.In this paper,a Ce-Zr based composite metal oxide catalyst was prepared by sol-gel method,characterized by TG/DTG,N2 physical stripping absorption,XRD,H2-TPR,NH3-TPD,O2-TPD and Raman,and the catalytic activities for VOCs degradation were tested using fixed bed reactor,.to study the relationship between the activity and the structure.The results of the experiment are as follows:(1)The mole ratio of Cu-Mn double metal influences the activity of CuxMnyCe0.75Zr0.25Oz catalysts.A series of CuxMnyCe0.75Zr0.25Oz catalysts were prepared by sol-gel method using citric acid as pore-making agent.The high activity of Cu1Mn0CZ for toluene degradation,with the complete toluene degradation(T100)of 240 ?,is attributed to the interaction between Cu-Ce metal and the lattice deformation caused by CuO into CeO2 lattice leads to more oxygen vacancy in catalyst,which is beneficial to the adsorption and activation of toluene molecule and oxygen species.(2)The degradation of toluene over CuCe0.75Zr0.25Ox is effected by the sol-gel form during catalysts preparation.It is found that the advantages of the BC with ultra fine three-dimension networks and excellent compatibility are beneficial to form gel with nitrate solution to prepare the mesoporous catalyst.The catalyst performances are significantly inflluenced by the gel-forms and gelling temperature during the catalyst preparing process.The T100 of ACCZ-70 prepared by alcohol gelling at 70 ? is 220 ? which is lower than those of the literatures,and the excellent activity of ACCZ-70 is ascribed to its low temperature reducibility and high concentration of oxygen vacancies(0.81).(3)The effects of calcination process on the VOCs degradation over CuCe0.75Zr0.25Ox catalyst were also explored in this study.The results show that the calcination process effects the activity of CuCe0.75Zr0.25Ox catalysts in the prepare process using bacterial cellulose with sol-gel method.The CuCe0.75Zr0.25Ox catalyst(Q450)with calcination temperature of 450 ? using rapid heating(10 ?/min)procedure,exhibits excellent activity with T100 of 220 ?.The high activity is attributed to the good low-temperature reduction of catalysts,highoxygen vacancy concentration(2.39)and the lattice distortion in the process of catalyst calcination.Besides,a competitive adsorption phenomenon was discovered over Q450 catalyst in the simultaneous degradation of n-heptane(750 ppm)and toluene(750 ppm).