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Study On Combustion Of Toluene Over Ceria-zirconia Solid Solution Catalyst

Posted on:2016-08-04Degree:MasterType:Thesis
Country:ChinaCandidate:H L WuFull Text:PDF
GTID:2311330536954684Subject:Environmental Science and Engineering
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Volatile organic compounds?VOCs?are a large class of vital air pollutants,its treatment technology is a hot topic in China and abroad.Catalytic combustion is a promising technology on removal of VOCs and the high-activity catalyst is the most important factor.This research prepared ceria-zirconia solid solution catalyst for catalytic combustion of volatile organic compounds.The catalytic properties were improved by doping one element and two combined elements.The modified catalysts were characterized by XRD,SEM,TEM,BET.The effect factors for catalytic combustion of toluene were tested.The ceria-zirconia solid solution catalyst prepared by sol-gel method had the best dispersion effect and catalytic activity.When the toluene initial concentration was 4000mg/m3,the space velocity was 6000h-1,the Ce-Zr ration was 0.6 to 0.4,the baking temperature was 550 degree,the catalyst had the best toluene conversion rate and the ignition temperature T50 and complete conversion temperature T90 of toluene were 302? and 352? respectively.From the XRD patterns it could be noted that Zr4+ can merge into ceria lattice and form cubic fluorite like ceria-zirconia solid solution.For one element doping,Ce0.6Zr0.35M0.05O2?M=Y?La?Mn?Cu?,the XRD patterns show that the doping element dispersed well and formed Ce-Zr-M three element solid solution.To reduce the reaction ignition temperature,doping Mn>La>Cu>Y.For improving high temperature stability,doping Y > Mn > La > Cu.When doping Mn and Y forming Ce0.6Zr0.3Mn0.05Y0.05O2,the catalyst had the best activity under both 550 degree and 950 degree baking,550 degree baking Ce0.6Zr0.3Mn0.05Y0.05O2 T50 is 260? and T90 is 327?.The surface area of Ce0.6Zr0.35Mn0.05O2 is 140.37m2/g and the surface area of Ce0.6Zr0.3Mn0.05Y0.05O2 is 145.94m2/g,both are larger than Ce0.6Zr0.4O2?87.3m2/g?.From combustion of toluene over Ce0.6Zr0.3Mn0.05Y0.05O2 catalyst experiment,we found that the conversion rate of toluene increased as S type with the increase of reaction temperature.When the toluene initial concentration was 4000mg/m3,baking temperature was 550 degree,particle diameter between 0.3 and 0.45 mm,the catalyst had the best toluene conversion rate.The catalyst can maintain high conversion rate when the space velocity was under 9000h-1.As the concentration of water vapor increased,the toluene conversion rate decreased.Through XRD,BET,SEM,TEM test,550 degree baking catalyst kept the cubic phase.The pore was mesoporous channel and the pore structure was long cylindrical with a diameter of 5nm.
Keywords/Search Tags:Volatile Organic Compounds, Toluene, Ceria-Zirconia Solid Solution, Catalytic combustion, Doping
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