城南学院半纤维素的红外及热解实验研究摘要本文利用红外光谱实验技术研究半纤维素的分子结构。通过分析红外光谱图,得出以下结论:在897cm-1附近有较强的振动吸收峰,表明糖单元之间以β-糖苷键连接1161~988cm-1之间的谱带是木聚糖的典型吸收峰,这说明半纤维素的成分以木糖为主,结构主要为吡喃环结构。1161cm-1处的弱吸收峰表示有阿拉伯糖基侧链的存在。结合红外光谱实验,整合前人的研究成果,获得简化了的半纤维素二聚体模型物的分子结构。实验结果和现有理论研究表明该结构模型是合理的采用热重分析法对木聚糖的热解特性进行实验研究。通过TG和DTG曲线的分析,把木聚糖的热解反应过程分为四个阶段。综合分析热解实验结果发现,30℃/min的升温速率是反应的最佳环境。由分子模拟计算结果,500K和700K分别对应热解实验的第二阶段和第三阶段。低温时半纤维素的热解反应进行得十分剧烈,主要对应半纤维素支链的断裂。随着温度的升高,半纤维素主链发生分解生成各种产物。实验结果和分子模拟的结果能够较好地吻合。关键词:半纤维素;分子模型;热解;微观反应机理ABSTRACT城南学院半纤维素的红外及热解实验研究Theinfraredspectrumexperimenttechnologyisappliedtostudythemolecularstructureofthehemicellulose.Wegotthefollowingconclusionsbyanalyzingtheinfraredspectrogram:Thereisastrongvibrationabsorptionpeakaround897cm-1,whichshowsthatthesugarunitsisconnectedbybeta-glycosidicbond.Thebandbetween1161~988cm-1isthetypicalabsorptionpeaksofxylan,whichsuggeststhatthemaincompositionofhemicelluloseisxyloseanditsmainstructureispyranring.Theweakabsorptionpeakat1161cm-1reflectsthatthereareArabcarbohydratesidechainsthere.Weobtainedthesimplifiedmolecularstructureofhemicellulosedimmermodelbycombininginfraredspectrumexperimentresultwiththefruitsofotherresearchers.Theexperimentalresultsandtheexistingtheoreticalmodelalsoshowsthatthemodelstructureisreasonable.Thermogravimetricanalysisisusedtoresearchthepyrolysischaracteristicsofxylan.ThexylanpyrolysisreactionprocessisdividedintofourstagesaccordingtotheTGandDTGcurves.Andthepyrolysisexperimentresulttellshat30/minheatingrateisthebestreactioncircumstance.Itisfound℃that500Kand700Krespectivelycorrespondingtothesecondstageofpyrolysisexperimentandthethirdstagebyanalyzedthemolecularsimulationresults.Pyrolysisreactionofhemicelluloseisseverewhenthetemperatureislow,mainlycorrespondingtheruptureofhemicellulosebranchedchain.Themainchainofthehemicellulosedecomposedtogenerateavarietyofproductswiththeincreaseoftemperature.Theexperimentalresultsandmolecularsimulationresultscanfitwell.KeyWords:Hemicellulose;Molecularmodel;Pyrolysis;Microscopicreactionmechan城南学院半纤维素的红外及热解实验研究目录第一章绪论.....................................................................................................11.1引言..................................................................................................................11.2生物质热解技术的研究现状.........................................................................11.2.1国外生物质热解应用现........................................................................11.2.2国内生物质热解技术研究...................................................................21.3半纤维素的研究概述......................................................................................41.3.1半纤维素的基本结构研究....................................................................41.3.2半纤维素热解特性.................................................................................51.4分子模拟生物质热解综述.....