PdCuAl2O3催化还原硝酸盐的研究张燕

:2002-07-19.　:　,,1971,,.:　.Tel:[phone];E-mail:[e-mail].:0253-9837(2003)04-0270-05:270～274Pd-Cu/γ-Al2O3张　燕1,　陈英旭2,　刘宏远3(1浙江大学土木系,浙江杭州310027;2浙江大学环境工程系,浙江杭州310029;3浙江工业大学建工学院,浙江杭州310014):,.Pd-Cu/γ-Al2O3,,、、H2.,Pd-Cu/γ-Al2O3,81%;,.,--,,73.4%89.4%.、,.:,,,,,,,:O643/X7　　　:ACatalyticReductionofNitrateinWateroverPd-Cu/γ-Al2O3CatalystZHANGYan1,CHENYingxu2,LIUHongyuan3(1DepartmentofCivilEngineering,ZhejiangUniversity,Hangzhou310027,Zhejiang,China;2DepartmentofEnvironmentalEngineering,ZhejiangUniversity,Hangzhou310029,Zhejiang,China;3CollegeofCivilEngineeringandArchitecture,ZhejiangUniversityofTechnology,Hangzhou310014,Zhejiang,China)Abstract:Theincreaseofnitrateconcentrationingroundwaterhasstimulatedtointensiveresearchondenitrifi-cation.CatalyticreductionofnitratebyasolidPd-Cubimetalliccatalystpresentsoneofthemostpromisingap-proachesforremovalofnitratefromwater.Inthiswork,thecatalyticreductionofnitrateinaqueoussolutionbypowdercatalystandceramicmembraneinabatchreactorwasinvestigated.ThenitratereductionwasstudiedasafunctionoftheinitialconcentrationandtheH2flux.TheresultsdemonstratedthatPd-Cu/γ-Al2O3caneffec-tivelyremovenitrate,thetotalnitrogenremovalefficiencyis81%.Thereductionactivityofnitrateandthefor-mationofammoniumaremainlycontrolledbythediffusionlimitationandthemasstransferofthereactants.Undertheconditionofdiffusioncontrolledortheintensificationofthemasstransfer,andagoodreactioncondi-tion,thePd-Cu/γ-Al2O3canreducetheamountsofammoniumwhileretaininghigherreactivity.Theceramicmembranecatalystcancreateahigheffectivegas/liquid/solidinterface,andshowshigherselectivityascom-paredwiththepowdercatalyst.Theselectivityfornitrogenwasimprovedfrom73.4%to89.4%.Thecatalyticreductionofnitratebyceramicmembraneshowsapromisingmethodfornitratereduction,especiallyforthesmall-scaleapplicationintheruralarea.Keywords:palladium,copper,alumina,supportedcatalyst,ceramicmembrane,nitrate,catalyticreduction,ammonium244　Vol.24No.4　　　　ChineseJournalofCatalysis　20034　April2003　　、,,[1～3].,,,[4,5].11.6mg/L,5.3mg/L;(USEPA)(WHO)10mg/L[6,7];200020mg/L10mg/L.,,.　　(、、、)NO-3.,、、[8～10],[11,12].,,,,;,,.　　,.,,[13,14].,,N2NH+4[13].,,,、.1　1.1　　　.γ-Al2O3(32μm),PdCl2(),,,100℃.350℃2h,NaBH4.,Pd/γ-Al2O3.Pd5%.Pd/Cu.Cu(NO3)2Pd/CuPd-Cu/γ-Al2O3.,Pd/Cu4.1.2　　　1.5L[15].900mlPd-Cu/γ-Al2O3,,H2,,NaNO3100ml,1000ml,.pH,(5.2±0.2)..(100mm,810mm),,.,.,,100mg/L,25℃,150kPa300ml/min.　　0.45μmNO-3,NO-2NH+4.pHS-3CpH;NO-3NO-2Dionex-120,NH+4,722λ=420nm.　　,.,,.1　Table1　ConcentrationofnitrateandammoniumandnitrogenremovaloverdifferentcatalystsCatalystρ(NO-3)/(mg/L)ρ(NH+4)/(mg/L)r(N)/%Pd/γ-Al2O382.12.658.2Pd-Cu/γ-Al2O304.3181.0Reactionconditions:ρ0(NO-3)=100mg/L,p(H2)=150kPa,qV(H2)=300ml/min,θ=25℃,t=60minr(N)Totalnitrogenremoval2　2.1　　　1Pd/γ-Al2O3Pd-Cu/γ-Al2O3.·271·4　:Pd-Cu/γ-Al2O3,Pd/γ-Al2O3,8.2%;Pd-Cu/γ-Al2O3,,81%;,,.Pd/γ-Al2O3,.Pd/γ-Al2O3,[15].Cu,,.　　1Pd-Cu/γ-Al2O3.1　4Pd-1Cu/γ-Al2O3Fig1　Temporalcurvesofnitrateremovalover4Pd-1Cu/γ-Al2O3catalyst(1)ρ(NO-3),(2)ρ(NH+4),(3)ρ(NO-2)2　Pd/CuFig2　EffectofPd/CuratiooncatalyticperformanceofPd-Cu/γ-Al2O3(1)Activity,(2)ρ(NH+4)　　2,Pd-Cu/γ-Al2O3Pd/Cu.,Pd/Cu,,;NH+4Pd/Cu.,n(Pd)/n(Cu)=4,.:Cu,PdCu,,;Cu,Cu,Pd,.2.2　　　,.Langmuir-Hinshelwood,3.,,(c0)(c),.3　Fig3　Catalyticreductionofnitratesolutionwithdifferentinitialconcentration　　4,H2,,,.,NO-2,NO,N2ON2,,,,.H2,,;,,,.　　·272·　　　　　　244　H2Fig4　CatalyticreductionofnitrateunderdifferentflowrateofH2(a)Nitrateconcentration,(b)AmmoniumconcentrationqV(H2):(1)100ml/min,(2)200ml/min,(3)300ml/min5　Fig5　EffectofPd-Cu/γ-Al2O3amountoncatalyticreductionofnitrate(1)Initialactivity,(2)ρ(NH+4),(3)ρmax(NO-2)5.,,,;,.:,,,Pd,,.,,,.[13],NOx.NOx,N-N,N2;NOxH2,N-H,H2NH+4.,NOxH2,N2.,,H2,N2.6　Fig6　Schematicdiagramofporoustubularcatalyticmembrane2.3　　　,,.,,.6.、、.·273·4　:Pd-Cu/γ-Al2O3　　7.,,,N2.7　Fig7　Temporalcurvesofnitrateremovalthroughceramiccatalyticmembrane(1)ρ(NO-3),(2)ρ(NH+4),(3)ρ(NO-2)　　8,,90%N2.,N273.4%.,,.,、、,,.8　Fig8　Catalyticreductionofnitrateoverdifferentcatalysts(1)AmountofN2fromNO-3conversion,(2)Ammoniumconcentration　　,,.100mg/L60min,.,80%.,.,,,,.,.1　StarkJM,HartSC.Nature,1997,385(6611):612　HaruvyN,HadasA,RavinaI,ShalhevetS.WaterSciTechnol,2000,42(1/2):1353　,.(SongXJ,DingTH.Envi-ronProt),1999,265(11):444　SuperM,HeeseHdeV,MacKenzieD,DempsterWS,duPlessisJ,FerreiraJJ.WaterRes,1981,15(11):12655　FreedmanDM,CantorKP,WardMH,HelzlsouerKJ.ArchivesEnvironHealth,2000,55(5):3266　SpaldingRF,ExnerME.JEnvironQual,1993,22(3):3927　LeeK-C,RittmannBE.WaterSciTechnol,2000,41(4/5):2198　BemsB,JentoftFC,Schl¨oglR.ApplCatalB,1999,20(2):1559　WisniewskiC,PersinF,CherifT,SandeauxR,GrasmickA,GavachC.Desalination,2001,139(1-3):19910　FanningJC.CoordChemRev,2000,199:15911　SoaresMIM.WaterRes,2002,36(5):139212　FlereJM,ZhangTC.JEnvironEng,1999,125(8):72113　HöroldS,VorlopK-D,TackeT,SellM.CatalToday,1993,17(1/2):2114　WärnaJ,TurunenI,SalmiT,MaunulaT.ChemEngSci,1994,49(24B):576315　,.(ZhangY,ChenYX.ChinaWaterWastewater),2002,18(9):47(EdWGZh)·274·　　　　　　24