钠、硅和硫在热解过程中的相互作用

钠、硅和硫在热解过程中的相互作用

我们有一个低等级的微芯片。从浅火的角度来看，这是一个浅火的区域。从浅火的角度来看，它是一个浅火的区域。如果是一个缓慢的步骤，它是一个缓慢的步骤。如果是一个缓慢的步骤，它是一个缓慢的步骤。如果是，参与制作微芯片。微芯片授权事务管理（icc）、微构建微芯片生产效率和微构建微芯片生产效率。Sodiumrichsulphateshavebeenfoundtobethekeycomponentswhichformlowmeltingpointeutecticsthatbindwithsilicatestoproduceastickymoltenashlayerwhichbondsbedmaterialduringcombustion.ItwouldbeexpectedthatduringFBGsodiumwouldreactwithsulphurtoformsodiumsulphideasopposedtosodiumsulphateduringcombustion.Theroleofsulphurintheformationoftheashdepositionlayerandagglomeratesundergasificationconditionsisnotwellunderstood,particularlyinFBG.DetailedSEM-EDXinvestigationsandX-raymappingofanAustralianlow-rankcoalsubjectedtoatemperature-programmedpyrolysiswereperformedtostudytheeffectofsodiumloadingonsulphurretention.This,alongwithwaterandacidleachingtestsofthesolublephasesofsodiumandsilicatosupportevidencefromtheSEMinvestigations,isalsopresented.1规训cortie.4和.3.4和.3.4和.3.4和.3.4和.3.4和.3.4和.和..4和.3.3.4和..3.4和...3.4年生理想同价................................3.3.4和3.4年...4和3.4年...3.3AnAustralianlow-rankcoal,inasizefractionof150μm～212μm,wasemployed.ThedetailedanalysesoftherawcoalarepresentedinTable1.Water-washingandacid-washingofthecoal(denotedasWWandAW)wereperformedbycontinuouslywashingwithdemineralisedwaterormixing250goftherawcoalwith1.0litreof0.5mol/LHClsolution,whichremovesacid-solubleminerals.Sodiumion-exchangedcoalsamplesarepreparedbymixingtheacid-washedcoalwith0.25mol/L,0.5mol/Land1.0mol/Lsolutionsofsodiumacetate,respectively.Thesamples(denotedasAW-Na(0.25mol/L),etc.)arethenwashedwithdemineralisedwatertoremoveexcesssodiumions.SulphurandinorganicanalysesofthesamplesarefeaturedinTable2.AllsamplesemployedintheexperimentsaredriedinN2at110℃untilthereisnofurthermassloss.Temperature-programmedpyrolysis(TPP)experimentsareconductedinamufflerfurnaceflushedwithN2at3L/min.～3gramsofeachsampleareplacedincrucibleslocatedinthefurnace,whichisheatedwithaconstantheatingrateof17.7℃/minfromtheambienttemperature.Preliminaryexperimentswithdifferentsamplemassesandcruciblesizesofferedthesamesulphurretentionandsulphurformdistributions,confirmingthattherearenointer-particlemassdiffusioneffects.TheAW-Na(0.5mol/L)samplewassubjectedtodifferentfinaltemperaturesbetween700℃and1000℃.Thesampleswereremovedassoonasadesiredtemperaturewasreached,quenchedwithdryice,andthenstoredforsubsequentanalysesasdescribedbelow.ProximateandultimateanalysesfollowedAustralianstandardAS2434.1/2/8andAS2434.6.1,respectively.TotalsulphurwasdeterminedusingAustralianStandards10.Inorganicsulphurforms,namely,sulphateandpyritesulphurcontentsofthecharsweredeterminedusingtheAustralianStandards1038.11.Organicsulphurwascalculatedbythedifference.H2SevolvedfromHCltreatmentwithasampleiscapturedbyaniodinesolutiontoindicatethesulphidecontentinthechar,amethodsimilartothatusedbyIbarraandGryglewicz.TheinorganicanalysisfortherawandAWcoals,wascarriedoutusingAustralianStandardsAS1038.11.SequentialwaterandacidleachingoftheAW-NacoalandTPPcharsamplesat900℃wascarriedouttodeterminethesolubleformsofsilicaandsodiumbeforeandafterpyrolysis.Amixtureof0.5gcoalorcharsample,50mLofdemineralisedwaterplus1.0mLethanolwasprepared,boiled,simmeredfor30minandwashedandthenfiltered.ThefiltratewasanalysedusingtheAS1038.11todeterminethewater-solubleNaandSicontent.Theresiduewasthenmixedwith50mLof2mol/LHCl,boiledandsimmeredfor30min.Afterfiltration,usingAS1038.11,thefiltratewasanalysedfortheacid-solubleformsofNaandSi,whiletheresiduewasanalysedtoprovidetheacid-insolublecontentofNaandSicompounds.BackscatteredelectronimagesoftheTPPcharsweretakenusingaPhilipsXL20ScanningElectronMicroscope(SEM).RandomspotquantitativeanalysisoforganicsulphurandmineralconstituentswasperformedwithanEnergyDispersiveX-raydetector(SEM-EDX).Toascertainwhetherthesulphurwasoforganicorinorganicnature,theatomicweightpercentofcorrespondinginorganicconstituentswasrecordedandatomicratiosofNa,CaandFetosulphurcalculated.ThequantitativeX-raymappingofcharswasobtained,providingindividualX-raymaps(iDXiX-raymaps)ofS,Si,Na,O,ClandinsomecasesAl,FeandCa.FortheX-raymapping,onlyweightconcentrationvaluesweretaken.2影响的神圣迪迪斯运营2.1u2004u2005Figure1presentsbackscatteredSEMimagesoftheAW-Na(0.5mol/L)charextractedbetween700℃and1000℃.Thewhiteinclusionsareclearlynoted.Theseinclusionswerewellformedaround900℃andstillpresentincharasthetemperatureincreasedto1000℃.TheiDXiX-raymapsofsulphur,sodium,silica,oxygenandchlorineconstituentsoftheAW-Nacharremovedat900℃arefeaturedinFigure2.ThesodiummapshowsthatduringTPP,sodiumformslargewhiteinclusionswithandaroundlargesilicainclusions.Sodiumalsoconcentratesascrystalswithinthecharparticleswhereonlyoxygenispresentwhileotherconstituentssuchassilica,carbonandchlorineareabsent.Intheabsenceofcarbon,itsuggeststhattheseintenseareasofsodiumareeitherNa2OorNaOHcompounds,theformerbeingmorelikely.Na2CO3hasameltingpointaround851℃,thereforeitislikelythatinthecurrentTPPexperiments,Na2CO3wouldhavedecomposedtoNa2Oasthepyrolysistemperaturereaches900℃.ItisinterestingthatoxygenispresentwiththesodiumandsulphursinceNa2SO4isnotexpectedtobeaproductofcoalpyrolysis.SEM-EDXspotanalysisonthesewhiteinclusionsinthecharrevealedtheatomicratiosofNa∶Srangingfrom5∶1to11∶1,suggestingneithersulphideorsulphate.Itislikelythattheseinclusionsbeganastheconcentratedconstituentsofsodium,whichhaveattractedandreactedwithsulphurevolvingfromthedecompositionoforganicsulphur,asobservedinX-raymapsinFigure2(ie.Na2O).Figure2providesevidencethatsulphurdoesinteractwithsodiumduringpyrolysis.2.2u2004范围Figure3(a)revealsthattheAW-NacoalsbeforeTPPcontainsignificantproportionsofNaintheacidsolublephase.Water-solubleNaisalsosignificantinthecoalwhichcanbeaccountedforastheNa+bondedtohumicacids.Figure3(a)alsoshowsthatthereisverylittleacid-insolublesodium,similartothatobtainedinapreviousstudyonthesamecoalbyYeetal,where0.03%sodiumremainedintheacid-washedcoal.TheAW-Nacoalsalsohaveverylittleacid-solublesilica,asshowninFigure4(a).Theacid-insolublesilicaismostlikelyintheformofquartz.Thereisnoindicationofwater-solublesilicafromtheseresults.However,goodcomparisonbetweenthetotalsilicadeducedfromashanalysisandsummationofacid-solubleandacid-insolublesilicainTable3revealsthatverylittlewater-solublesilicaexistedinthecoalbeforeTPP.ComparisonofthesolubilitiesofsodiumintheAW-Nacoalbefore(Figure3(a))andafter(Figure3(b))TPPshowsthatacid-soluble(organicallybound)sodiumisconvertedtobothwater-solubleandacid-insolublephases.Asmentionedbefore,Na2CO3andNaOHarethelikelyproductsfromtheconversionoforganicallyboundNa+duringdevolatilisation.ThesecompoundsdecomposetoNa2Otoconstitutepartofthewater-solublesodium.Ifanysodiumsulphide(Na2S)forms,theywillalsobepresentinthisphaseaswell.Sodiumishighlymobileandmayreactwithsilicainclusions.Duetothecorrespondingincreaseinwater-solublesilicainFigure4(b),itislikelythatwater-solublesodiumsilicates(suchasNa2Si2O5,Na2SiO3,andNa4SiO4)alsoaccountforthesignificantwater-solublesodiuminthecharat900℃.Table3summarisestheweightpercentagesofwater-soluble,acid-solubleandacid-insolublesodiumandsilicaintheAW-NacoalandcharremovedfromTPPat900℃.Table4displaystheweightpercentagesofwater-solublesodium.Thesodiumtosilicaratiosinthewater-solublephaseareintheorderof3.5to4.7,indicatingthattheamountofsodiumrequiredtoformwater-solublesilicatesismorethansufficient.Thisthereforejustifiesthepresenceofintenseregionsofsodium/oxygencrystalsobservedfromSEMimages,representingotherwater-solublesodiumcompoundssuchasNa2O.Figure2(b)indicatesthatitispossiblethatover60%ofthequartz(SiOx)reactswithsodiumtoformwater-solublesodiumsilicates.About5%～10%oftheoriginalsilicatransformstowaterinsoluble/acid-solublesilicatesinthecharafterTPP,whichislikelytobeduetotheformationofsodiumaluminosilicatesuchasNa2O·AlO2·SiO3.Thehighmolarratioofacid-solublesodiumtosilicainTable4thereforeindicatesthatthisonlyaccountsforsomeoftheacidsolublesodiumdetectedinthecharalong.Theexcessofsodiumimpliesthatmostoftheacid-solublesodiumisorganically-boundtothecoalmatrix,theremainingacid-insolublesilicabeingun-reactedquartz.TheX-raymapsshowthatconcentratedareasofsilicacanexistintheabsenceofsodiumwithinthewhiteinclusions.Figure3(b)indicatesthatafterpyrolysis,approximately20%ofthetotalsodiuminthecharisacid-insoluble.Sodiumdoesnotformacid-insolublecompoundswithsilica.TheX-raymapsrevealthatsodiumexistsinthecharswithsilicainwater-solubleform,whilesomeremainsorganicallyboundinthecharorincrystalswithoxygenandsulphur.Figure5showsthebackscatteredSEMimagesofAW-Na+(0.5mol/L)charsremovedat700℃and800℃andthenwashedwithhydrochloricacidbeforetheSEManalysis.TwodifferentmagnificationsoftheSEMimagesforsamplesextractedfromeachofthetwotemperaturesarepresentedforclarity.Theobservedwhiteinclusionsembeddedincharparticles,comprisingmainlyofsodiumandsulphur,suggestseither(a)theacid-washingofTPPcharandtheacidleachinganalysisprocedurewasnotabletoremovetheembedded,otherwiseacid-solublesodium/sulphurconstituents,thusgivingrisetothenotionthatduringpyrolysisacid-insolublesodium/sulphurconstituentsform,or(b)acid-insolublesulphur/sodiumconstituentsdoformduringpyrolysisduetointeractionsbetweenorganically-boundsodiumandsulphur.Theformerreason(a)ispossiblesincethereactionsbetweenorganically-boundsodiumandsulphurarelikelytoformmicro-grainsofmineralsdeeplyembeddedinthechar.Thelatterreason(b),however,explainsthedetectionofacid-insolublesodiuminthecharasindicatedinFigure3(b).2.3非负性acid-solu催化剂—TheeffectofsodiumacetateconcentrationFurtherSEManalysesreaffirmthattheinfluenceofNa+ionsonthetotalsulphurisnotaresultofsulphide(Na2S)formingmechanismandthatsulphurisassociatedwithsodiuminanacid-insolubleforminthechar.Toconfirmwhethertheorganicallyboundsodiumhadanyeffectontheformationoftheacid-insolublesulphur/sodiumconstituents,thevariousformsofsodiumwereinvestigatedwithvaryingNaAcconcentrationandaresummarisedinFigure3(aandb),asdiscussedearlier.TheeffectofNaAcconcentrationontheacidsolubleformsofsilicaispresentedinFigure4(aandb).Figure3(a)doesnotshowanycleartrendsofsodiumsolubilitywithincreasingconcentrationofsodiumacetate.Themainreasonforthismayagainlieintheion-exchangeproceduresfortheAW-Na(0.5mol/L)coal.Figure3(b)showsthatbothwater-solubleandacid-insolublesodiumincreaseinthecharastheNaAcconcentrationincreases,attheexpenseofacid-solublesodium.Foracid-insolublesodium,theincreaseismorepronouncedastheconcentrationascendsfrom0.25mol/Lto0.5mol/L.ThisimpliesthatduringTPP,theretentionoforganicsulphurcanincreaseupto10%oftotalsulphurwhenthecontentoforganically-boundsodiumionsincreasesfrom2%(0.25mol/LNaAc)to3%(0.5mol/LNaAc).Sincethereisanupperlimittotheamountoforganicallyboundsodiumduetosaturationofcarboxylicgroups,thereisalsoanupperlimittotheamountofacid-insolublesulphur/sodiumconstituentsthatcanform.3．相关因子和so对so对so对sophigreune,solu发展Thepresentworkrevealedthatpartoftheorganicallyboundsodiumformswater-solubleNa2CO3andNa2Ocompounds,andasignificantproportionofwater-solublesodiumsilicates.Thelatterappearsaslargeinclusionsincharparticles.Highlyconcentratedregionsofsulphuraroundtheedgesoftheinclusionsis