金属有机骨架材料(MOFs)ppt课件

.,MetalOrganicFrameworks,TeamMembers:CaoChangFuChuXianReporter:DuMengYuan,.,PublishedonNatureReviewsMaterials,.,CONTENTS,.,Introduction,1,.,Metalorganicframeworks(MOFs)areascientificallycompellingandfunctionallyevolvingclassofmeso-,micro-andultramicroporousmaterials.MOFstructuresencompassdozensoftopologies,includingseveral,suchassodaliteandRho,thatarealsowellknownforzeolites.MOFshavebeenexploredformanyapplicationsincluding,butnotlimitedto,gasstorageandrelease,chemicalseparations,drugdelivery,catalysis,lightharvestingandenergyconversion,and,recently,thedegradationoftoxicsubstancessuchaschemicalwarfareagents,.,MOFsarecomposedofmetalnodesandorganiclinkersthatcanbesystematicallytunedintermsofchemicalcompositionandprecisearrangementanattributethatdiffersfrompurelyinorganiczeolites,whichconsistlargelyofsiliconoraluminiumionslinkedbyoxygenatoms.,.,Inrecentyears,thenumberanddiversityofMOFstructureshavegrownsignificantly,andmanywater-stableandthermallystableMOFsnowexist,Enablinganexcitingexpansionoftheirapplication.Dependingontheapplicationenvisaged,differentfunctionalstabilitiesareimportant.,.,Stabilityofmetalorganicframeworks,2,.,Stabilityisdefinedasresistanceofthestructuretodegradation.However,anotherpossibledefinitionisthermodynamicinorigin:manyfunctionallystableMOFs(aswellaszeolites)arethermodynamicallyunstablewithrespecttoalternativetypically,denserpolymorphs.AnactiveareaofMOFresearchisthedevelopmentofroutestothermodynamicallyunstable,butfunctionallystable,polymorphs.,.,Stabilityofmetalorganicframeworks,.,1,Chemicalstability,ThegreatestconcernsfortheimprovementofMOFchemicalstabilityhavebeenlargelyrelatedtoliquidwaterandwatervapour;accordingly,wefocusonaqueoussolutions.InmostMOFstructures,thechemicalweakpointsareatthenodesmorespecifically,themetallinkerbondswithhydrolysisyieldingaprotonatedlinkerandahydroxide(orwater)ligatednode.Acidicsolutionscanacceleratetheformationoftheformer,andbasicsolutionscanacceleratetheformationofthelatter.AlthoughthereisnostandardmethodforassessingthestabilityofMOFsinacidic,basicorneutralsolutions,itisoftenjudgedbycomparingthepowderX-raydiffraction(PXRD)patternofaMOFbeforeandaftersoakingitinagivenaqueoussolution.,.,Thechemical(acidbase)stabilityofsomerepresentativemetalorganicframeworksbasedonliteraturedata.ThebarlengthindicatesthepHrangethatthemetalorganicframeworks(MOFs)cantolerate.AnarrowindicatesthattheMOFcanwithstandpH14.,.,Selectedsectionsofrepresentativemetalorganicframeworkmaterialsa|ZIF-8b|Cu-BTTric|MIL-53(Al)d|MIL-101(Cr)e|PCN-426-Cr(iii)f|(CH3)2NH22Eu6(3-OH)8(1,4-NDC)6(H2O)6.,.,ConnectivityofZr6nodesinzirconium-basedmetalorganicframeworksandtheassociatedcarboxylatemoleculesrequiredtolinknodestogether.,.,2,Thermalstability,ThermaldegradationofMOFsis,inmostcases,aresultofnodelinkerbondbreakage,accompaniedorfollowedbylinkercombustion.Asaconsequence,thermalstabilityisgenerallyrelatedtonodelinkerbondstrengthandthenumberoflinkersconnectedtoeachnode.Frameworkcatenationmorespecifically,interpenetrationorinterweavingofnetworkscanenhancestabilitythroughfavourableframeworkframeworkinteractions.Thermogravimetricanalysis(TGA)andinsituPXRDarebothtechniquesthatcanbeusedtogaugethethermalstabilityofMOFs.,.,3,Hydrothermalstability,Experimentally,hydrothermalstabilityisassessedbyexposingMOFstosteamatvariouspressuresandtemperatures,followedbyPXRDanalysisandporosityorsurface-areameasurements.MOFhydrothermalstabilitycanbeenhancedbyintermolecularorintramolecularforces,suchasinternalhydrogenbondingorstacking.ZIFsasaclasscompriseexcellentexamplesofhydrophobicMOFs,andmanyZIFsarehydrothermallystable,makingthemreasonablecandidatesforuseinhumidconditions.,.,4,Mechanicalstability,MOFsareknownfortheirextraordinaryporosityanattributethatinherentlydecreasesmechanicalstability.Therefore,asexpected,MOFsarelessmechanicallystablethanzeolites.Thisinstabilitycanmanifestitselfasphasechanges,partialcollapseofporesorevenamorphization,inresponsetomechanicalloading.SomearrangementsoflinkersandconnectorsrenderMOFsmoreresistanttodeformationanddestructionthanothers.Somecomputationalstudiesshowthatmechanicalstabilitytendstobeenhancedwithshorterlinkers.AnimportantpracticaldevelopmentthatgreatlyreducesthemechanicalperformancerequirementsforMOFsinapplications.,.,MOFstabilityincatalyticsystems,3,.,Thecatalyticactivesitecanbeseveraldifferentlocationswithinthestructure.ItcanbeincorporatedintheMOFlinkersornodes,orencapsulated,isolatedorstabilizedbyaMOF,orattachedtotheframeworkpostsynthetically.Regardlessofthemethodusedtointroducecatalyticallyactivesites,theframeworkmustbestableundercatalysisconditions.,.,MOFstabilityincatalyticsystems,.,1,Solution-phasecatalysis,Thiscanconstituteacidic,neutralorbasicconditions.Morespecifically,theMOFcatalystsneedtobeabletowithstandtheconditionsappropriateforthechosenreaction.,.,CatalyticoxidationofwaterusingIr-containingderivativesofUiO-67.TheimageshowsthestructureofUiO-67andIr-containinglinkers1and2thatareutilizedforwateroxidationcatalysisatpH1.,.,Catalytichydrolysisofthenerveagentsoman(knownasGD)byNU-1000,.,2,High-temperaturecatalysisofgas-phasereactions,TheuseofMOFsforgas-phasecatalysisisinanearlyphase,andmostinvestigationshavefocusedonproof-ofconceptreactionssuchastheoxidationofCOtoCO2.WebelievethatthenotionofMOFsasstableanduniformsupportsforsingle-sitecatalystsisanespeciallyexcitingone,meritingfurtherdevelopment.,.,OxidativedehydrogenationofcyclohexenetobenzeneusingV-UiO-66asacatalyst,.,Futureperspectives,4,.,Thee