β-o-4型木质素模型化合物热解机理的研究

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1、万方数据华北电力大学硕士学位论文AbstractThecurrentpredicamentofexhaustingfossil如elsandaggraVatingenViromnentalproblemscanbeexpectedtobesolVedbytheutilizationofbiomass．Ligninisanabundantnaturalpolymer-Ithasthepotentialtoproducearomaticcompounds，thuspartiaUyreplacingthef-ossil如els．Duringthef．astpyrolysisoflign

2、in，bio-oilrichinaromaticcompoundscanbeproduced．StudyonthepyrolysismechaIlismofligninwillproVidetheoreticalbasisfortheselectiVecontrolofthepyrolysisprocess，thusitiscmcialf-ordeVelopingefhcients‘；：lectiVepyrolysistechnology．Inthisstudy，density向nctionaltheory(DFT)wasemployedtostudythepyrolysisme

3、chanismsofligninmodelcompoundswithp一0-4linkages：(1)TheinitialdecompositionmechanismofG够peligninmodeldimerwithp-O—4linkage(Guaiacylglycerol-p—guaiacylEther)wasstudied．Sixinitialdec锄positionmechanisms，includingCp—Ohomolyticdecomposition，C旺一Cphom蛳icdecomposition，concerteddeconlposition，etc．werec

4、ompared．TheresultsindicatethattheCB一0homolyticdecompositionhasthelowestenergybarrier，anditisthemostfaVorablereactionduringtheinitialdecompositionofthemodeldimer．(2)BondDissociationEnergies(BDEs)oftheCB—Obondsin14ligninmodelconlI×Hmdswithp—O-4linkageswerecalculated．Theeffectsofthehydroxylandme

5、thoxylgroupsatdimrentpositionsontheBDEswerediscussed．Theinteractionsbe佃．eendi虢rentgroupswerealsostudied．TheresldtsindicatethatthereisminorinnuenceofthehydroxylgroupatCa．ThehydroxylgroupatCYhardlyaffectstheBDEwhenthereisnomethoxylgroupatR2．HoweVer，whenthereismethoxylgroup‘atR2，hydrogenbondwinb

6、ef．onnedbetweenthehydroxylgroupatC7andthemethoxylgroupatR2，andthus，thespatialstructureofthemodelcompoundwillbestrengtllenedandtheBDEisincreased．ThemethoxylgroupsatR2andR3canlowertheBDEsindifferentdegreesbecauseofthepossiblehydrogenbondbetweenthemethoxylgroupatR乏andhydroxylgroupatCy．Themethoxy

7、lgroupatRlhasminorefrectsontheBDE．MoreoVer，itdoesnotparticipateintheinteractionswithother劬ctionalgroups．(3)FortheinitialmechanismsofGuaiacylglycerol-p—guaiacylEtherwithrelatiVelowerene唱ybaHiers，funherdetailedstudyonthesubsequentpathwayswascar