简介:建立了电感耦合等离子体发射光谱法测定镍铬合金中Si,Mn,Fe,Ti,A1,Cu元素含量的分析方法。确定了溶样方法和分析谱线,采用基体匹配消除干扰。对方法精密度和准确度进行实验,实验结果表明,各元素的相对标准偏差均小于3%,加标回收率在86.8%~106.9%,镍铬合金标准物质的各元素测定结果均与标准值一致。所建立的方法快速、准确,适用于镍铬合金中多元素同时测定。
简介:为研制具有较宽频带微波吸收性能的材料,采用机械合金化法制备CoxFe80-xSi20(x=0,6,10,14摩尔百分数)合金粉体,使用SEM、XRD和矢量网络分析仪等测试手段,研究了合金粉体微观结构及Co-Fe-Si合金微波吸收性能。结果表明:制备的合金粉末呈片状,主要由-Fe相组成;Co的添加使Co-Fe-Si合金出现两个微波吸收峰。在较高频段处的微波吸收峰值随Co的添加先增大后减小。在涂层厚度为1.8mm时,x=10的合金低频处的反射率最小值最小,合金吸波峰频率和峰值分别为6.2GHz和-14.8dB,合金在高频处吸波峰频率和峰值分别为18GHz和-8.8GHz,合金反射率低于-5dB的带宽达14GHz,具有良好的微波吸收宽频效应。
简介:ThecorrelationbetweenphasestructuresandsurfaceacidityofAl2O3supportscalcinedatdifferenttemperaturesandthecatalyticperformanceofNi/Al2O3catalystsintheproductionofsyntheticnaturalgas(SNG)viaCOmethanationwassystematicallyinvestigated.Aseriesof10wt%NiO/Al2O3catalystswerepreparedbytheconventionalimpregnationmethod,andthephasestructuresandsurfaceacidityofAl2O3supportswereadjustedbycalciningthecommercialγ-Al2O3atdifferenttemperatures(600–1200C).COmethanationreactionwascarriedoutinthetemperaturerangeof300–600Catdifferentweighthourlyspacevelocities(WHSV=30000and120000mL·g-1h-1)andpressures(0.1and3.0MPa).ItwasfoundthathighcalcinationtemperaturenotonlyledtothegrowthinNiparticlesize,butalsoweakenedtheinteractionbetweenNinanoparticlesandAl2O3supportsduetotherapiddecreaseofthespecificsurfaceareaandacidityofAl2O3supports.Interestingly,NicatalystssupportedonAl2O3calcinedat1200C(Ni/Al2O3-1200)exhibitedthebestcatalyticactivityforCOmethanationunderdifferentreactionconditions.LifetimereactiontestsalsoindicatedthatNi/Al2O3-1200wasthemostactiveandstablecatalystcomparedwiththeotherthreecatalysts,whosesupportswerecalcinedatlowertemperatures(600,800and1000C).ThesefindingswouldthereforebehelpfultodevelopNi/Al2O3methanationcatalystforSNGproduction.
简介:ThedetailedkineticsofFischer-TropschsynthesisoveranindustrialFe/Cu/La/Sicatalystwasstudiedinacontinuousspinningbasketreactorundertheconditionsrelevanttoindustrialoperations.ReactionrateequationswerederivedonthebasisofLangmuir-HinshelwoodHougen-WatsontypemodelsforFischer-Tropschsynthesisbasedonpossiblereactionssetsoriginatedfromthecarbide,enolicandcombinedenol/carbidemechanisms.Kineticmodelcandidateswereevaluatedbytheglobaloptimizationofkineticparameters,whichwererealizedbyfirstminimizationofmulti-responseobjectivefunctionswithconventionalLevenberg-Marquardtmethod.Itwasfoundthatanenolicmechanismbasedmodelcouldproduceagoodfitoftheexperimentaldata.Theactivationenergyforparaffinformationis95kJmol-1whichissmallerthanthatforolefinformation(121kJmol-1).
简介:WepresentthetemperaturedependentelectricaltransportmeasurementsofAg/Si(111)-(√3×√3)R30°bytheinsitumicro-four-pointprobemethodintegratedwithscanningtunnelingmicroscopy.Thesurfacestructurecharacterizationsshowhexagonalpatternsatroomtemperature,whichsupportstheinequivalenttriangle(IET)model.Ametal-insulatortransitionoccursat-115K.Thelowtemperaturetransportmeasurementsclearlyrevealthestronglocalizationcharacteristicsoftheinsulatingphase.
简介:IncorporationofstrontiumintoV-Moalumina-supportedcatalystenhanceditsperformance(increasedconversionandselectivity,decreasedreducibilityandimprovedstability)inpropaneoxydehydrogenationtopropylene.12.5%SrloadingwasshowntobetheoptimumcontenttotheV-Mocatalyst.Theresultsweresupportedbyvariouscharacterizationtechniques,namely,BET,XRD,SEM,FTIRandTPD.
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:Ni-CobimetalliccatalystswithdifferentNi/Cocontentwerederivedfromcoldplasmajetdecompositionandreductionofhydrotalcite-likecompoundscontainingNi,Co,MgandAl,andtheircatalyticperformancewasinvestigatedwithdryreformingofmethane.Experimentalresultsshowedthatthehydrotalcite-likeprecursorscouldbecompletelydecomposedandpartlyreducedbycoldplasmajet,andtheNicontainedcatalystsexhibitedmuchhigheractivitythanthecatalystwithoutNi.Especially,thecatalystwithNi/Coratioof8/2achievednotonlythehighestconversionsof80.3%and69.3%forCH4andCO2,respectively,butalsothebeststabilityin100htesting.ThecatalystswerecharacterizedbyXRD,XPS,TEMandN2adsorptiontechniques,andtheresultsshowedthatthebetterperformanceofthe8Ni2Cobimetalliccatalystwasattributedtoitshighermetaldispersion,smallermetalparticlesize,aswellastheinteractioneffectbetweenNiandCo,whichwerebroughtbythespecialcatalystpreparationmethod.
简介:HydrotalciteprecursorsofLamodifiedNi-Al2O3andNi-SiO2catalystspreparedbyco-precipitationmethodandthecatalyticactivitieswereexaminedfortheproductionofCOx-freeH2byCH4decomposition.Physico-chemicalcharacteristicsoffresh,reducedandusedcatalystswereevaluatedbyXRD,TPRandO2pulsechemisorptions,TEMandBET-SAtechniques.XRDstudiesshowedphasesduetohydrotalcite-likeprecursorsinovendriedformproduceddispersedNiOspeciesuponcalcinationinstaticairabove450C.Ramanspectraofdeactivatedsamplesrevealedthepresenceofbothorderedanddisorderedformsofcarbon.Ni-La-Al2O3catalystwithamoleratioofNi:La:Al=2:0.1:0.9exhibitedtremendouslyhighlongevitywithahydrogenproductionrateof1300molH2mol1Ni.AdirectrelationshipbetweenNimetalsurfaceareaandhydrogenyieldswasestablished.
简介:通过水热法合成了一维链状的磷钼氧酸盐(DETA)。NaNa(H5P4Mo6O31)2]·8H2O(DETA—Diethylenetriamine),采用x-射线单品衍射结构分析,元素分析和红外光谱等表征.该磷钼氧酸盐属于三斜晶系,空间群是P-1,晶胞参数a=1.2434(3)nm,6—1.2610(3)nm,c=1.3079(3)nm,a=85.418(3)°,β=73.399(2)°),γ=82.175(3)°,V=1.9450(8)Elm。,F(000)=1462,Z=:=2.标题化合物的结构是由Na(H5P4Mo6O31)2簇单元,二亚乙基三胺阳离子和结晶水分子组成.另外,Na(H5P4Mo6O31)2簇由钠离子连接形成了一维的链结构.一维链结构又由于二亚乙基三胺阳离子和结晶水分子形成的氢键进一步连接三维超分子结构.用标题化合物修饰的碳糊电极(APM—CPE)对AA氧化有很好的电催化活性.
简介:标题化合物(C30H35N3)以4-甲基苯甲醛、环十二酮和3-甲基-1-苯基-1H-吡唑-5-胺,在三氟乙酸和醋酸的作用下,经微波辐射合成得到.其结构通过单晶X射线衍射法确定,晶体属单斜晶系,空间群P21/c,相对分子质量Mr=437.61,晶胞参数a=1.08926(11)nm,b=2.1927(2)nm,c=1.04954(14)nm,V=2.4641(5)nm3,Z=4,晶胞密度Dc=1.180g/m3,吸收系数μ=0.069mm-1,单胞中电子的数目F(000)=944.晶体结构用直接法解出,经全矩阵最小二乘法对原子参数进行修正,最终的偏离因子为R=0.0468,ωR=0.0905.在晶体结构中新形成的吡啶环为共平面结构.