用EXAFS研究NiO在γ-Al_2O_3表面上的分散-豆柴文库

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用EXAFS研究NiO在γ-Al_2O_3表面上的分散
Abstract
ThedispersionofNiOonγ-Al_2O_3surfacewasstudiedusingextendedX-rayabsorptionfinestructure(EXAFS)spectroscopy.ThesynthesizedcatalystwascharacterizedusingX-raydiffraction(XRD)andtransmissionelectronmicroscopy(TEM).ThedispersionofNiOonγ-Al_2O_3surfacewasexaminedbyEXAFSspectroscopyandtheresultsindicatedthatNiOwaswell-dispersedonthesurfaceofγ-Al_2O_3.
Introduction
Catalystsplayacrucialroleinmodernsocietyastheyareusedinawiderangeofchemicalprocesses.Thedispersionoftheactivemetalspeciesonthesupportisoneofthemostimportantfactorsthataffecttheperformanceofcatalysts.Inparticular,thedegreeofdispersionaffectsthesurfaceareaoftheactivemetalspecies,whichinturnaffectsthenumberofactivesitesavailableforcatalysis.
NiOisanimportantactivemetalspeciesusedinmanyindustrialprocessesasithashighthermalstabilityandgoodcatalyticproperties.γ-Al_2O_3iscommonlyusedasasupportforNiOasithasahighsurfaceareaandgoodmechanicalproperties.ThedispersionofNiOonthesurfaceofγ-Al_2O_3iscriticalforitscatalyticactivity,andthereforeunderstandingthefactorsthataffectthedispersionisimportant.
EXAFSspectroscopyisausefultechniqueforstudyingthedispersionofmetalspeciesonasupportasitprovidesinformationonthelocalstructureofthemetalspecies.Inthisstudy,weusedEXAFSspectroscopytoinvestigatethedispersionofNiOonthesurfaceofγ-Al_2O_3.
Experimental
NiOwassynthesizedusingahydrothermalmethod.ThesynthesizedNiOwascharacterizedusingXRDandTEMtoconfirmthecrystalstructureandmorphologyoftheparticles.TheNiOwasthendepositedontothesurfaceofγ-Al_2O_3usinganincipientwetnessimpregnationmethod.
EXAFSspectroscopywascarriedoutattheNationalSynchrotronRadiationResearchCenter(NSRRC)inTaiwanusingathird-generationsynchrotronradiationbeamline.TheNiK-edgeEXAFSspectrumwasrecordedusingafluorescencedetector.TheEXAFSspectrawereanalyzedusingtheArtemispackageintheDemetersoftwaresuite.
ResultsandDiscussion
TheXRDpatternofNiOshowedsharppeakscorrespondingtothewell-definedcrystalstructureofNiO,whichconfirmedthepurityofthesample.TheT