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简介：TheexternalsurfaceofHZSM-5zeolitewaspassivatedbyliquidsiliceousdepositionandbyacidicsitespoisoningwithlepidine,respectively.Thenmethanol-to-hydrocarbons(MTH)reactionwasinvestigatedovertheaboveas-preparedcatalystsandthedissolublecokeontheseusedcatalystswasanalyzedbyGC-MS,tostudytheroleoftheexternalsurfaceofHZSM-5inthecatalyticreaction.ComparisonwiththeexperimentalresultsbasedonparentZSM-5showedthattheproductdistributionofMTHreactionwasobviouslyinfluencedbytheexternalsurface.Evidenceswerelistedasfollows:(1)thefinalproductonparentHZSM-5showedhigheraromaticselectivity,lowerolefinselectivity,lowerratioofC2/C3+aliphaticsandhigherratioofC3/C4+aliphaticsthanthereactionmixtureproducedbythesolecatalysisofacidicsitesinHZSM-5channel;(2)alittleofpentamethylbenzeneandhexamethylbenzeneintheproductonparentHZSM-5,wasproducedviamulti-methylationofmethylbenzeneontheexternalsurface.TheaboveconclusionmayalsobesuitableforMTHreactionoverotherzeoliteswith10-ringchannel.

简介：BimetallicFe-Mnnanocatalystssupportedoncarbonnanotubes(CNTs)werepreparedusingmicroemulsiontechniquewithwater-to-surfactantratiosof0.4-1.6.ThenanocatalystswereextensivelycharacterizedbydifferentmethodsandtheiractivityandselectivityinFischer-Tropschsynthesis(FTS)havebeenassessedinafixed-bedmicroreactor.Thephysicochemicalpropertiesandperformanceofthenanocatalystswerecomparedwiththecatalystpreparedbyimpregnationmethod.Verynarrowparticlesizedistributionhasbeenproducedbythemicroemulsiontechniqueatrelativelyhighloadingofactivemetal.TEMimagesshowedthatsmallmetalnanoparticlesintherangeof3–7nmwerenotonlyconfinedinsidetheCNTsbutalsolocatedontheoutersurfaceoftheCNTs.Usingmicroemulsiontechniquewithwatertosurfactantratioof0.4decreasedtheaverageironparticlesizesto5.1nm.Thereductionpercentageanddispersionpercentagewerealmostdoubled.Activityandselectivitywerefoundtobedependentonthecatalystpreparationmethodandaverageironparticlesize.COconversionandFTSrateincreasedfrom49.1%to71.0%and0.144to0.289gHC/(gcath),respectively.WhiletheWGSratedecreasedfrom0.097to0.056gCO2/(gcath).C5+liquidhydrocarbonsselectivitydecreasedslightlyandolefinsselectivityalmostdoubled.

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简介：Effectsofspacevelocity,reactiontemperatureandsupportacidityonproductdistributionandinductionperiodin1-buteneisomerizationandmetathesisoverMo/mordenite-aluminawereinvestigated.Asrevealedbythecatalyticperformanceresults,inductionperiodandobjectiveproductwerecloselyrelatedtothereactionconditions.Lowerspacevelocityledtolongerinductionperiodandhigherpropeneyield.Theoptimalreactiontemperatureforpropeneproductionisaround150Canditshiftedto100Cforetheneproduction.1-Buteneauto-metathesispredominatedinthereactionnetworkifthesupportwithlowerdegreeofsodiumexchanged.Andpropenegraduallybecamethedominantproductuponincreasingthesupportsodiumexchangedegree.6Mo/H100Na0M-30Alcatalystwithasupportoffullsodiumexchangedegreeexhibitedthehighestpropeneyield.