Study On TiO₂ Composite Catalysts Modyfied By Doping N,Fe,Ag And Its Photocatalytic Elimination Of Some Alcohols

This paper introduces the development of the photocatalytic chemistry,the hazard of volatile organic pollutants and governance,the research status of TiO₂ photocatalytic elimination of organic pollutants and modified by doping.N,Fe,Ag.The damage and control and of VOCs,developmental actuality,practical and academic meaning of photo-catalytic chemistry have been summarized in this article, especially photo-catalytic degradation mechanism and research actuality of organic pollutants over TiO₂ and the alteration of TiO₂ have been expounded in detail. A series of photocatalysts have been prepared by sol-gel and dep-pre methods,and characterized by IR,TG-DTA,SEM,XRD and XPS.A flowing-continual photo-catalytic reaction setting was designed and fixed,in which the photo-catalytic elimination of methanol(or ethanol) was used as model reaction to evaluate the photo-catalytic activity of catalysts under ultraviolet light irradiation.The preparation conditions of catalysts such as adulteration,activation temperature and time have been discussed and optimized.The influence of gas flow rate and methanol(or ethanol) concentration on elimination has been studied.The photocatalytic elimination of the methanol was used as a model reaction to evaluate the photocatalytic activity of the Ag/TiO₂ power catalyst under ultraviolet light irradiation. The effects of doped content,activation temperature and time,initial concentration of methanol and gas flow rate on the catalytic activity were investigated.The results show that the catalytic activity of Ag/TiO₂ power catalyst was significantly higher than un-doped TiO₂, the photocatalytic activity of the TiO₂ gets enhanced by doping moderate Ag.When the initial concentration of methanol is 10.0g.m^-3,the elimination of the methanol is basically completed under the flow rate of 5 mL.min^-1 over the 0.15 g Ag/TiO₂ power catalyst,which conforms to the requirements of emission standards for air pollutants.When its initial concentration is 10.0 g.m^-3 and the flow rate is 2 mL.min^-1,the conversion rate of the methanol is 100%,which has been mineralized completely。 The photocatalytic elimination of the methanol was used as a model reaction to evaluate the photocatalytic activity of the N/TiO₂ power catalyst under ultraviolet light irradiation.The effects of doped content,activation temperature and time,initial concentration of methanol and gas flow rate on the catalytic activity were investigated.The results show that the photocatalytic activity of the TiO₂ gets enhanced by doping N.When the initial concentration of methanol is 10.6g.m^-3,the elimination rate of the methanol is 96.6%under the flow rate 3 ml.min^-1,which can meet the emission standard of air pollutants.When its initial concentration is 10.6 g.m^-3 and the flow rate is 2ml.min^-1,the conversion rate of the methanol is 100%,which has been mineralized completely.The catalyst of N,Fe/TiO₂ activated under 400℃for 3h has the highest activity.When the initial concentration of methanol is 7.8g.m^-3 and the flow rate is 10ml.min^-1,the eliminate rate of methanol can reach to 88.97%;When the flow rate decreased to 7ml.min^-1, the methanol was completely eliminated.We also study the photocatalytic activity of elimination of ethanol.When the initial concentration of ethanol is 5.5g.m^-3,flow rate is 7ml.min^-1,the elimination rate of the ethanol is 98.73%;When the flow rate decreased to 5ml.min^-1,the ethanol was completely eliminated,the conversion rate of the ethanol is 100%.The apparatus for evaluating activity of photocatalysts in the experiment is scientific and practical,so data of the experiment are reliable.Compared with pure TiO₂,the activity of adulterated photocatalysts is higher,possesing a good practical prospect.