简介:钛酸铝系复合材料中钛酸铝的体积分数不同,会导致Al2TiO5/Al2O3复合材料的抗铝液浸渗性能的不同。在Al2TiO5中分别按10%、20%、40%、60%、80%、90%(体积分数)引入Al2O3进行复合。通过对渗铝试样的外观形貌、微观结构分析,进而对其铝液浸渗性能进行了分析比较,发现富钛酸铝的钛酸铝/氧化铝复合材料(妒(AL2TiO5)〉40%)抗铝液浸渗性能好;而富氧化铝的钛酸铝/氧化铝复合材料(φ(Al2TiO5)〈20%)有金属铝液沿热震产生的裂纹渗入复合材料内部,容易导致复合材料断裂失效。该研究结果对可靠应用钛酸铝系复合材料作为铝液的容器具有实际工程应用价值。
简介:0.5%Pt-K/γ-Al2O3catalystsforthesynthesisofo-phenylphenol(OPP)fromo-cyclohexenyl-cyclohexanone(dimer)dehydrogenationwerepreparedbymeansofatwosubsequentimpregnationmethod.Theeffectsofcatalystpreparationparameters,suchasKpromoters,calcination,andreductionconditions,wereinvestigated.TheresultsshowedthattheadditionofK2SO4toPt/γ-Al2O3catalystnotablypromotedtheselectivityofOPP,anditsoptimumcontentwasfoundtobe6%inmassfraction.ThehigheractivitywasobtainedwhenPt/γ-Al2O3catalystwascalcinedinnitrogenatmosphereat400―500°Candthenreducedatthesametemperaturefor3hinhydrogenatmosphere.TheconversionofthedimerandtheselectivityofOPPwerealwaysabove99%and90%,respectively,over0.5%Pt-6%K2SO4/γ-Al2O3catalystduringthepilotscaletestof8000h.
简介:Thispaperreportsonthelongevityofglycerol-dry(CO2)reformingoverthelanthanum(La)promotedNi/Al2O3catalysts.TheXRDresultsshowedthattheNiparticlewaswell-dispersedinthepresenceofLapromoter.Inaddition,viatheNH3-TPDanalysis,itwasfoundthattheLapromoterhasreducedtheacidityofNicatalystwhichmayhaveexplainedthemitigationofcarbonlaydown.Itwasdeterminedthatthe3.0wt%La-promotedNi/Al2O3catalystpossessedthelargestBETspecificsurfaceareaof97m2g-1.Consequently,ityieldedthebestcatalyticlongevityperformancewithconversionattainedmorethan90%,evenafter72hofreactionduration.Significantly,itcanbeconfirmedthatthepresenceofCO2duringtheglyceroldryreformingwasessentialinreducingcarbondeposition,mostlikelyviagasificationpathway.Thishasensuredastabilityofcatalyticactivityforalongreactionperiod(72h).
简介:ThedistributionsoftheaxialstressandshearstressinAl2O3-TiC/Q235diffusionbondedjointswerestudiedusingfiniteelementmethod(FEM).Theeffectofinterlayerthicknessontheaxialstressandshearstresswasalsoinvestigated.Theresultsindicatethatthegradientsoftheaxialstressandshearstressaregreatnearthejointedge.ThemaximalshearstressproducesattheinterfaceoftheAl2O3-TiCandTiinterlayer.WiththeincreaseofCuinterlayerthickness,themagnitudesoftheaxialstressandshearstressfirstdecreaseandthenincrease.Thedistributionoftheaxialstresschangesgreatlywithalittlechangeintheshearstress.TheshearfractureinitiatesattheinterfaceoftheAl2O3-TiC/TiinterlayerwithhighshearstressandthenpropagatestotheAl2O3-TiCside,whichisconsistentwiththestressFEMcalculatingresults.
简介:Thisworkinvestigatedthethermo-gravimetric(TG)changeandexplosionresistanceofultra-lowcementAl2O3-SiO2castablesaddedwith0,5%,10%,15%and20%of≤74μmrawbauxitepowderscontaining72.8%Al2O3,respectively.Thecastableswerepreparedusingwhitefusedaluminaasaggregate,powdersofwhitefusedalumina,fusedmullite,α-Al2O3ultrafines,3%CAcementand5%microsilicaasthematrixportion.TGchangeofthecastableswasinvestigatedbyathermo-gravimetricanalyzerforlargesizespecimen.Whentherawbauxiteadditionislessthan10%,themass-losingbehaviorofthecastablesissimilartothatwithoutrawbauxite,tendingtoreachaconstantmassaround400℃,beforewhichthemass-lossismildandproducinglittledestructiveinfluence.Withmorethan10%rawbauxiteaddition,however,themass-lossincreasessignificantly,andthetemperaturetoreachaconstantmassincreasesto600℃orhigher,unfavorabletostructuralstabilization.Withtherawbauxiteadditionupto20%,nonegativeinfluenceonexplosionresistanceisfound.
简介:Pd-containingionicliquid(IL)1-hexyl-3-methylimidazoliumtetrafluoroborate(C6MIMBF4)immobilizedon7-Al2O3(Pd-IL/γ-Al2O3)waspreparedandcharacterizedbyFouriertransforminfraredspectroscopy(FTIR),scanningelectronmicroscopy(SEM)andBrunauer-Emmett-Teller(BET)analysis.TheinfluencesofC6MIMBF4loadingandPdonmethaneconversiontoC2hydrocarbonsundercoldplasmawereinvestigated.FTIRandSEManalysesindicatedthatC6MIMBF4hadbeensuccessfullyimmobilizedon7-Al2O3andtheC6MIMBF4showedexcellentstabilityundercoldplasma.TheresultsofBETandmethaneconversionshowedthatwiththeincreaseinimmobilizationamountofC6MIMBF4ontoγ-Al2O3,thespecificsurfaceareaandporevolumeofIL/γ-Al2O3decreased,whiletheselectivityandyieldofC2hydrocarbonsincreased.TheselectivityofC2hydrocarbonswas94.6%whentheloadingofC6MIMBF4was40%,andthepercentageofC2H4inC2hydrocarbonswasashighas64%whenusingPd-IL/γ-Al2O3asacatalystwithnoconventionalthermalreductiontreatment.Opticalemissionspectra(OES)fromthecoldplasmareactorduringmethaneconversionwerealsostudied.TheresultsindicatedthattheintensityoftheC2,CH,H,andCactivespeciesfrommethaneandhydrogendecompositionincreasedwhenIL/γ-Al2O3orPd-IL/γ-Al2O3wasintroducedintotheplasmasystem.BasedontheanalysesofthegasproductandOESspectra,itcanbeconcludedthatthesurfacecatalyzedreactionsbetweenplasmaandionicliquidwereveryimportantforthereductionofPd2+andtheformationofC2H4.
简介:Inthecurrentpaper,dry(CO2)-reformingofglycerol,anewreformingroute,wascarriedoutoveralumina(Al2O3)-supported,non-promotedandlanthanum-promotednickel(Ni)catalysts.Bothsetsofcatalystsweresynthesizedviaawetco-impregnationprocedure.Physicochemicalcharacterizationofthecatalystsshowedthatthepromotedcatalystpossessedsmallermetalcrystallitesize,hencehighermetaldispersioncomparedtothevirginNi/Al2O3catalyst.ThiswasalsocorroboratedbythesurfaceimagescapturedbytheFESEManalysis.Fromtemperature-programmedcalcinationanalysis,thederivativeweightprofilesrevealedtwopeaks,whichrepresentawatereliminationpeakatatemperaturerangeof373to473Kfollowedbynickelnitratedecompositionfrom473to573K.Inaddition,BETsurfaceareameasurementsgave85.0m2g-1forthenon-promotedNicatalyst,whilstthepromotedcatalystsshowedanaverageof1%to6%improvementdependingontheLaloadings.Significantly,reactionstudiesat873KshowedthatglyceroldryreformingsuccessfullyproducedH2.The2%La-Ni/Al2O3catalyst,whichpossessedthelargestBETsurfacearea,gaveanoptimumH2generation(9.70%)ataglycerolconversionof24.5%.
简介:LocalstructuresofthemolybdenumsulfidespeciesinthesultidedRh-Mo-K/Al2O3catalystswithvariousrhodiumloadingshavebeeninvestigatedbyXAFS.Fromthefittingresults.theMo-Mocoordinationnumberforthesamplefreeofrhodium(ca.3.7)issimilartothatforthecrystallineMoS2,indicatingthatthesupportedsulfidedmolybdenumspeciesmainlypresentaslargepatechesofMoS2-likeslabs.Fortherhodium-modifiedsamples,however,theamplitudesoftheMo-SandMo-Mocoordinationshellsaresharplyreduced,revealingahighdispersionoftheMoS2-likespeciesinthecatalysts,TheschemeofthemicrostructuresofthesulfidedmolybdenumspeciesstabilizedonthealuminasupportisdiscussedbasedupontheanalysisoftheEXAFSdata.
简介:采用XRD、EXAFS技术研究了不同Pd含量的Pd-Mo-K/Al2O3催化剂结构,并关联其合成低碳混合醇性能。结果表明,在氧化态Mo-K/Al2O3催化剂体系中添加Pd后,“K-Mo”物相晶粒变小,分散度提高,说明钯可能和钾钼物种发生了较强的相互作用。经硫化还原处理后,发生了氧硫交换,钼主要以MoS2物种形式存在,其粒度随着Pd含量的增加而明显减小。尺寸的显著变化可能导致MoS2与载体作用形式的改变,从而影响CO加氢催化反应的性能。在硫化态催化剂中,Pd的添加不仅能提高CO加氢合成醇的收率和选择性,而且有利于改善产物的分布。基于以上结果,认为“K-Mo”作用物种和Pd物种均为合成醇的催化活性组份,它们间的相互协同作用使催化剂性能得到显著改善。