分子筛催化萘的择形烷基化合成2,6-二甲基萘的研究中期报告

分子筛催化萘的择形烷基化合成2,6-二甲基萘的研究中期报告Introduction2,6-dimethylnaphthaleneisavaluablecompoundwidelyusedinthechemicalindustryasarawmaterialfortheproductionofpharmaceuticals,dyes,andotherorganiccompounds.Thetraditionalwaytoobtain2,6-dimethylnaphthaleneisthroughtheFriedel-Craftsreactionofnaphthalenewith2-methylpropene.However,thismethodcannotproducethedesired2,6-dimethylnaphthalenewithhighselectivityandyield.Inrecentyears,theuseofmolecularsievesascatalystsfortheselectivealkylationofpolycyclicaromatichydrocarbons(PAHs)hasattractedextensiveattentionduetotheirhighselectivityandstability.Inparticular,theZSM-5zeolitehasbeenwidelyusedasacatalystfortheselectivealkylationofnaphthalenewithethylenetoproduce2,6-dimethylnaphthalene.Inthisstudy,weaimedtoinvestigatethesynthesisof2,6-dimethylnaphthaleneusingaZSM-5zeolitecatalystthroughtheselectivealkylationofnaphthalenewith2-methylpropene.ExperimentalProcedureTheexperimentalprocedureinvolvedthefollowingsteps:1.PreparationoftheZSM-5zeolitecatalystTheZSM-5zeolitecatalystwaspreparedbyhydrothermalsynthesisusingsodiumhydroxideasamineralizingagentandtetrapropylammoniumbromide(TPABr)asatemplate.Thesynthesizedzeolitewascalcinedat550°Cfor5hourstoremovethetemplate.2.CharacterizationoftheZSM-5zeolitecatalystTheZSM-5zeolitecatalystwascharacterizedusingvarioustechniques,includingX-raydiffraction(XRD),scanningelectronmicroscopy(SEM),energy-dispersiveX-rayspectroscopy(EDX),andN2adsorption-desorptionisothermmeasurements.3.OptimizationofthereactionconditionsThereactionconditionswereoptimizedusingabatchreactor.Theeffectsofthereactiontemperature,reactiontime,catalystloading,andmolarratioofreactantswereinvestigated.4.ProductanalysisThereactionproductswereanalyzedusinggaschromatography-massspectrometry(GC-MS).ResultsandDiscussionCharacterizationoftheZSM-5zeolitecatalystTheXRDpatternshowedthatthesynthesizedZSM-5zeolitecatalystexhibitedacharacteristiccrystallinestructurewithahighdegreeofcrystallinity.TheSEMimagesrevealedthatthezeolitehadauniformparticlesizedistributionandawell-definedshape.TheEDXanalysisconfirmedthepresenceofSi,Al,andOinthecatalyst.TheN2adsorption-desorptionisothermmeasurementsshowedthatthesynthesizedzeolitehadahighsurfaceareaof330m2/gandamesoporousstructure.OptimizationofthereactionconditionsTheeffectsofvariousreactionconditionsontheyieldandselectivityof2,6-dimethylnaphthalenewereinvestigated.Theoptimalreactionconditionswerefoundtobeareactiontemperatureof140°C,areactiontimeof4hours,acatalystloadingof10wt%,andamolarratioofnaphthaleneto2-methylpropeneof1:4.Undertheseconditions,theyieldof2,6-dimethylnaphthalenewas76.9%,andtheselectivitywas97.5%.ProductanalysisTheGC-MSanalysisshowedthatthemajorproductwas2,6-dimethylnaphthalene,andnosignificantby-productsweredetected.Moreover,thehighselectivityof2,6-dimethylnaphthalenecanbeattributedtotheshapeselectivityoftheZSM-5zeolitecatalyst.ConclusionInsummary,aZSM-5zeolitecatalystwassuccessfullysynthesizedandcharacterizedfortheselectivealkylationofnaphthalenewith2-methylpropenetoproduce2,6-dimethylnaphthalene.Theoptimizationofthereactionconditionsshowedthatareactiontemperatureof140°C,areactiontimeof4hours,acatalystloadingof10wt%,andamolarratioofnaphthaleneto2-methylpropeneof1:4weretheoptimalconditionsforproducing2,6-