预览加载中，请您耐心等待几秒...

果糖在酸性环境中脱水制备5-羟甲基糠醛的理论研究(英文).docx

预览
1/3
2/3
3/3

在线预览结束，喜欢就下载吧，查找使用更方便

下载提示 文本预览

如果您无法下载资料，请参考说明：

1、部分资料下载需要金币，请确保您的账户上有足够的金币

2、已购买过的文档，再次下载不重复扣费

3、资料包下载后请先用软件解压，在使用对应软件打开

果糖在酸性环境中脱水制备5-羟甲基糠醛的理论研究(英文) Thetheoreticalresearchonthedehydrationoffructoseinacidicenvironmentforthepreparationof5-hydroxymethylfurfural Introduction: 5-hydroxymethylfurfural(HMF)isaversatileplatformchemicalthathasattractedmuchattentioninrecentyearsduetoitspotentialapplicationsintheproductionofvariouschemicals,includingbiofuels,polymers,andpharmaceuticals.HMFcanbesynthesizedfromdifferentbiomassfeedstocks,andoneofthemostpromisingsourcesisfructose.FructoseisanaturalsugarfoundinfruitsandhoneyandcanbeeasilyconvertedtoHMFbydehydrationinanacidicenvironment.ThepurposeofthispaperistopresentatheoreticalstudyonthedehydrationoffructosetoHMFinanacidicenvironment,focusingonthereactionmechanism,theeffectofvariousparameters,andtheoptimizationoftheprocess. Reactionmechanism: ThedehydrationoffructosetoHMFinanacidicenvironmentfollowsastepwisereactionmechanism.Thefirststepistheprotonationofthefructosemoleculebytheacidcatalyst,whichgeneratesafructosecation.Thisstepisconsideredtobetherate-determiningstep,andthereactionrateishighlydependentontheacidconcentration.Thefructosecationthenundergoesdehydrationtoformacyclicintermediatecalledfructosedehydrationproduct(FDP).FDPisakeyintermediateinthereaction,anditsformationisfollowedbyitsrearrangementtoform5-hydroxymethyl-2-furaldehyde(HMF).Theoverallreactionschemeisshownbelow: Fructose→Fructosecation→FDP→HMF Effectofvariousparameters: SeveralparameterscaninfluencethedehydrationoffructosetoHMFinanacidicenvironment,includingtheacidconcentration,temperature,reactiontime,andwatercontent.Theeffectofeachparameteronthereactionrateandyieldisdiscussedbelow. Acidconcentration:Theacidconcentrationisthemostcriticalparameteraffectingthereactionrateandyield.Toolowacidconcentrationresultsinaslowreactionrate,whiletoohighacidconcentrationcanleadtosidereactionsandloweryields.Generally,asulfuricacidconcentrationof0.1-0.5MisusedforfructosedehydrationtoHMF,andtheoptimumconcentrationdependsonthereactionconditionsandthefructosesource. Temperature:Thetemperaturealsoaf