cuocexzr1xo2tio2催化剂nh3选择性催化还原柴油机nox的基础研究word格式论文.docxVIP

ABSTRACTCurrently,selectivecatalyticreduction(SCR)withammoniaisregardedasoneof the most efficient technologies for the abatement ofNOxemissionsfrom diesel engine，whichhasbeenextensivelyconcernedindevelopednations.Ce-/Zr-additivesareusedasaleveragingsolutiontopromptthestabilityoftheCu/TiO2,enlargetemperature windowandenhancetheSCRactivityaswell.AseriesofCuCexZr1-x/TiO2catalysts werepreparedbyacurrentlywetimpregnationwithanexcessofdeionizedwater. The physic-chemical properties andthereaction mechanismofthesecatalysts are characterizedbyBET,XRD,TEM,XPS,H2-TPR,NH3-TPD,NO-TPDandInsitu DRIFT.Theresearchresultsarecrucialinboththeoreticalsignificanceandpractical applicationtoreducedieselengineNOxemissionandadaptthemorestrictemission. Main conclusions from this studyare as follows:CuCe0.25Zr0.75/TiO2sampleexhibited nearly100%NOxconversion overawide temperaturerange(165-450oC),whichisstrikinglysuperiortothoseof Cu/TiO2(210–389°C).The zirconium and/or cerium introduction promote copper dispersion andinhibitcopper crystallization.Theamorphouscopperclustersformed contribute towideningthe activitywindow.Zirconiumand/orceriumdopingisalsobeneficialtopromotingcopperspecies enrichmentonthesurfacesofTiO2grains,promotingthetransferofmassand energyduringtheSCRprocess.Moreover,CuCe0.25Zr0.75/Tihasthehighest Oα/Oα+Oβratio,whichisvaluablefortheNOoxidationtoNO2intheSCR reaction and then facilitate the “fast SCR” reaction.Theredoxpropertyseemstoplayasignificantpartintheprocessofthe NH3-SCR.FromH2-TPRresults,itisfoundthattheadditionofzirconium and/orcerium,αreductionpeaksshiftmoderatelytolowertemperaturesand thepeakintensitiesincrease.Itindicatesthattheadditionofzirconiumand/or ceriumtoCu/Ticatalystenhancethesurfaceredoxability atlowtemperatures, whichleadstopromotetheSCRactivityunderlowtemperatures.Moreover, partial copper species have been incorporated into the vacant sites of zirconium oxidesorceriumoxidestocomeintobeingcoordinatedsurfacestructurewith thecappingoxygen,whichleadstolatticed