理论与计算催化

李微雪催化基础国家重点实验室中国科学院大连化学物理研究所理论与计算催化现代催化研究方法高级讲习班四川大学，成都2012.7.28-8.3多相催化催化作用：提高反应速率石油炼制、合成氨、汽车尾气排放挑战新催化材料控制催化活性本质原子尺度上实现催化剂的设计催化、表面、理论NobelPrize(2007)G.Ertl(Fritz-HaberInstituteMPG)ChemicalProcessofSolidSurfaceNobelPrize(1998)W.KohnDensityFunctionalTheory1918NobelPrizeFritzHaberAmmoniaSynthesisAmmoniasynthesisHeterogeneouscatalysis:interdisciplinaryresearchfieldPtFeOElectronicStructureTheoryBondMaking&BreakingSurfaceScienceStructureSpectroscopySupportedNano-ParticlesSize,Shape,SMSIElevatedT/PUHVZerotemperature理论与计算催化结构、组分电子结构催化功能活性、选择性理解优化预言+实验合作研究实用催化剂Theoryofheterogeneouscatalysis•Detailedtreatmentofspecificreactions–Insightintothequalityoftheoreticalmethods(DFT)–Detailedcomparisontoexperiments–Specificexamplesoftheprinciplesbehind•heterogeneouscatalysis–Understandingoftrends–Insightintogeneralparametersdeterminingthecatalyticactivity(rateandselectivity)ofacatalyticreaction.–Basis(eventually)fordesign.MultiscaleProcessAbinitioatomisticthermodynamicsandstatisticalmechanicsofsurfacepropertiesandfunctionsK.Reuter,C.StampflandM.Scheffler,in:HandbookofMaterialsModeling,PartA.Methods,(Ed.)SidneyYip,Springer(Berlin,2005).DensityFunctionalTheoryStatisticsMechanicsThermodynamics理论与计算催化LiteralquotefromKohnandSham’spaper:“…Wedonotexpectanaccuratedescriptionofchemicalbinding.”WalterKohn,NobelPrize1998Chemistry研究方法：密度泛函理论(DFT)NoblePrize3.4篇/期DFT+GGA密度泛函理论介绍ElectronicstructuretheorycalculationsofsurfacesTight-bindingDensity-functionaltheoryQuantumchemicalmethods(HF)(QuantumMonteCarlo)-Totalenergy-Forces(relaxation,vibrations,MD…)-Electronicstructure(…)But:manageablesystemsizes~500atomsvs.GGA/LDA交换关联近似：存在问题•弱相互作用(范德化、氢键）•分子氧的键能：误差～1eV•CO在金属表面上的吸附位•能带带隙严重低估•电子局域还是离域•稀土元素、3d金属氧化物•杂化泛函，+U一、合成气选择性转化二、催化氧化的活性相三、动力学四、活性中心认识机理揭示结构预示催化功能费托合成Fe,Co,烷烃Rh含氧化合物机理CO活化碳链增长含氧化物生成选择性、活性是关键合成气选择性转化问题：甲酰基寿命短，表征困难，机理不清一氧化碳的可控活化(Rh、Co)不依赖石油的能源、化工CHOCHCHOCHCOCHCOCHxxxx含氧化物生成(Rh)OCHCHCHOCHCHCHCHCHxxyxyx碳链增长(Co)OCHCHOHCOOCHHOCHCOCOactivation:directorhydrogenassistantdissociation?COactivationonCo(0001)CO*HCO*HCOH*CH*+OH*M.Ojeda,M.Mavrikakis,E.Iglesia,J.Catal.272(2010)287COactivationonRh(111)Y.H.ZhaoandW.X.LiinpreparationHOMOHCOCOd-bandFreeMoleculeTMLUMOElectronicStructureFormationEnergyofHCOCO+1/2H2HCO1.12eVGasPhaseRh(111)1.07eVCo(0001)1.05eVThoughconcentrationslower,buthighlyactive!COHCOHCOversusCOInsertionandCarbeneCouplingY.H.Zhao,andW.X.Li,Angew.Chem.Int.Ed.50(2011)5335Y.Zhao,W.X.Li*,Angew.Chem.Int.Ed.50(2011)5335铑、钴催化剂HCO插入较CO插入有利甲酰基插入和碳链增长能垒相当结构不敏感甲酰基:碳链增长/含氧化物的重要中间体HCOversusCarbeneCouplingHCOY.H.Zhao,andW.X.Li,Angew.Chem.Int.Ed.50(2011)5335HCOinsertionCHO+CH2~0.75eV(Rh)CHO+CH2~0.17eV(Co)CarbenecouplingfromRef.[1]:CH2+CH2,3~0.89eV(Rh)CH2+CH2~0.20eV(Co)[1]J.ChengandP.Hu,Top.Catal.53(2010)326HCOinsertioniscompetitivetocarbenecoupling甲酰基:碳链增长/含氧化物的重要中间体铑：高含氧化物选择性钴：高烷烃选择性O/Rh键～235kJO/Co键～291kJORHCRHCOY.Zhao,W.X.Li*,Angew.Chem.Int.Ed.50(2011)5335减少贵金属Rh催化剂含氧化物的选择性：烷基与CO插入反应和加氢反应的竞争COCHCOCHxx结构、组分敏感1xxCHHCH结构、组分不敏感加入惰性组分，弱化CO吸附、减少贵金属用量减少贵金属Rh催化剂利用配体效应降低CO插入能垒，提高含氧化物选择性：Y.H.Zhao,H.Y.Su,W.X.Li,J.Phys.Chem.C.115(2011)18247X.F.Ma,H.Y.Su,W.X.Li,Catal.Today160(2011)2280.29eV(加氢，RhCu)0.48eV(加氢,Rh)22002100200019001800Cucoverage(ML)3.01.00.50.30.1PM-IRASIntensity(a.u.)Wavenumber(cm-1)CO/xMLCu/5MLRh/SiO2PCO=2x10-6torr0.0212520782069203501230.02.0x10-24.0x10-26.0x10-28.0x10-21.0x10-1SiO2/Mo(110)P=510torrCO:C2H4:H2=1:1:15450Kfor60minC3H6OTOF(molecules/site/sec)Cu(ML)Cu/SiO25MLRh/xMLCu/SiO2C2H4+CO+H2CH3CH2CHOCO吸附变弱Y.X.Yao,X.F.Ma,W.Goodman,W.X.Li,inpreparation活性提高四倍RhCu合金：乙烯氢甲酰化RhCu合金：乙烯氢甲酰化-0.50.00.51.01.5(a)(b)FSTSIS-0.180.17-0.31-0.160.370.591.37Energy(eV)0.49FSTSISRhRhCuCOinsertionHydrogenationY.X.Yao,X.F.Ma,W.Goodman,W.X.Li,inpreparation一、合成气选择性转化二、催化氧化的活性相三、动力学四、活性中心认识机理揭示结构预示催化功能催化氧化的活性相氧化反应条件下的活性相、及其反应机理Langmuir-Hinshelwood机理MarsvanKrevelen机理O2CO2COOXIDE金属氧化物On-andsub-surfaceoxygen:(111)SurfaceoffccmetalOxygenbondstrengthatbasalTMsurfacesScTiVCrMnFeCoNiCuZnYZrNbMoTcRuRhPdAgCdLaHfTaWReOsIrPtAuHgM.TodorovaW.X.Lietal.,Phys.Rev.Lett.89,096103(2002)`O(2x1)O(2x2)O(1x1)3O(2x2)StrongvariationwithelementandcoveragehollowsitesEFReviews:B.HammerandJ.K.NørskovC.StampflandM.SchefflerRuRhPdAgO2pO2pO2pO2pd-bandfillingOaObOTheRoleoftheO-AgInteractioninthefunctionofSilverasanOxidationCatalystC2H4+1/2O2C2H4OActiveoxygenandStructureismissingW.X.Lietal.,Phys.Rev.B,68,165412(2003),Phys.Rev.B.67,045408(2003),Phys.Rev.B,65,075407(2002)HereinandBaoetal,Zeit.Phys.,1996FromUHVtoRealWorld(TheoreticalRecipes)AbinitioatomisticthermodynamicsSubstrateSurfaceGasPhaseGO,Metal(T,P):GibbsfreeenergyafteradsorptionW.X.Lietal,Phy.Rev.B68,165412(2003)),(),(),(),(OxygenMetalMetalOxygen,MetalOxygen,PTNPTGPTGPTGGibbsFormationEnergyofAdsorptionGibbsfreeenergyExtendedSystem:G(T,P)=Etot+Fvib+pVEtotInternalenergyfromDFTpVV=V(T,P)fromequationofstateofsolid,varieslittleFvib(T,V)VibrationFreeEnergyfromphononbandstructureMoleculeinGasPhase:μO(T,p)=μO(T,p0)+1/2kBTln(p/p0)fromthermo-chemicaltablesatp0=1atm.Upperlimit:½E(O2)O-richconditionandzeroreferen