简介：Theinteractionsofoxidativeradicals(Br2,HOetc.)withN-phosphoryldipeptidederivatives(NDM-TrpOMeandNDT-MetOMe)havebeeninvestigatedbyusingpulseradiolysisatdifferentpHvalues.IthasbeenfoundthatBr2andHOradicalsoxidizetheMet-siteandTrp-siteinthedipeptidederivativesviaformationofthethree-electron-bondedintermediateandindolylradicalsimultaneously.Thentheintramolecularelectrontransferalongthepeptidebackboneoccurs.Therateconstantsofelectrontransfer,k,havebeendeterminedandthereactionmechanismhasbeendeduced.

简介：Theoxidativesplittingprocessofcis-syn1,3-dimethyluracilcyclobutanedimer(DMUD)inaqueoussolutionwasinvestigatedusingpulseradiolysistechnique.TheresultsindicatedthatDMUDcanbesplittedinto1,3-dimethyluracil(DMU)byOHradicals(OH)andBr2radicalanions(Br2^-),butnotbyazideradicals(N3^).TheoxidativemechanismsthatanH-abstractedfromDMUDforOHoxidativesplittingandanelectrontransferfromDMUDtoBr2-,weresuggested.Relatedkineticparametersweredetermined.

简介：Athree-dimensionalgeometricmodeloftheoxidativecouplingofmethane(OCM)packed-bedreactorloadedwithNa2WO4-Mn/SiO2particulatecatalystwassetup,andanimprovedStanschkineticmodelwasestablishedtocalculatetheOCMreactionsusingthecomputationalfluiddynamicsmethodandFluentsoftware.Thesimulationconditionswerecompletelythesamewiththeexperimentalconditionsthatthevolumevelocityofthereactantwas80mL/minunderstandardstate,theratioofCH4/O2was3,thetemperatureandpressurewere800°Cand1atm,respectively.Thecontourofthecharacteristicsparametersinthecatalystbedwasanalyzed,suchasthespeciesmassfractions,temperature,theheatfluxonsidewallsurface,pressure,fluiddensityandvelocity.TheresultsshowedthatthecalculatedvaluesmatchedwellwiththeexperimentalvaluesontheconversionofCH4andtheselectivitytoproducts(C2H6,C2H4,CO2,CO)inthereactoroutletwithanerrorrangeof±2%.ThemassfractionsofCH4andO2decreasedfrom0.6and0.4inthecatalystbedinletto0.436and0.142intheoutlet,wherethemassfractionsofC2H6,C2H4,COandCO2were0.035,0.061,0.032and0.106,respectively.Duetotheexistenceoflaminarboundarylayer,thecontoursofeachcomponentbentupwardsinthevicinityoftheboundarylayer.ThisOCMreactionwasvolumeincreasereactionandthetotalmolesofproductsweregreaterthanthoseofreactants.Theflowfieldinthecatalystbedmaintainedconstanttemperatureandpressure.Thefluiddensitydecreasedgraduallyfrom2.28kg/m3intheinletofthecatalystbedto2.22kg/m3intheoutletofthecatalystbed,whilethevelocityincreasedfrom0.108m/sto0.115m/s.

简介：Biodiesel(fattyacidalkylesters),analternatetofossilfuel,hasthetendencyofautoxidationandhencerequiresantioxidantsforlongtermstorage.TheinfluenceofsyntheticandnaturalantioxidantsontheoxidativestabilitywasanalysedforfreshFAMEs(fattyacidmethylesters)obtainedfromheveabrasiliensisat140C.HigheractivitywasobservedforsyntheticantioxidantsfollowingtheorderofGA>BHT>DTBP>Q>GT-M>PH-M>GT-C,whereastheoxidativestabilityofstoredFAMEssamplesmeasuredat110Crevealsanearlyinversetrend.StoragestabilitywastestedfortheFAMEsobtainedfromheveabrasiliensisstoredat30C,afteradditionofsyntheticandnaturalantioxidants—butylatedhydroxytoluene(BHT),2,6-di-tert-butylphenol(DTBP),quercetin(Q),gallicacid(GA),methanolextractsfromgreentea(GTM),pomegranatehull(PH-M),andchloroformextractofgreentea(GT-C).Antioxidantactivitiesabove1500ppmwasintheorderofDTBP>BHT>GA>GT-C>GT-M>Q>PH-M.SyntheticantioxidantshavebeenfoundmoreefficienttoimprovethestoragestabilityofFAMEsobtainedfromheveabrasiliensis.DTBPinparticularhasthehighestprotectionfactor.

简介：ＯｘｉｄａｔｉｖｅＤｅｈｙｄｒｏｇｅｎａｔｉｏｎｏｆＩｓｏｂｕｔａｎｅｔｏＩｓｏｂｕｔｙｌｅｎｅｏｖｅｒＦ￣－ＭｏｄｉｆｉｅｄＲａｒｅＥａｒｔｈＭｅｔａｌＯｘｉｄｅＣａｔａｌｙｓｔｓＺＨＡＮＧＷｅｉ－ｄｅ，ＴＡＮＧＤｉｎｇ－ｌｉａｎｇ，ＬＡＩＷｅｎ－...

简介：AsimplemethodfortheoxidativearomatizationofHantzsch1,4-dihydropyridinestothecorrespondingpyridinesisachievedbyusinghydrogenperoxideasgreenoxidantandaceticacidascatalystinaqueoussolution.

简介：Isotacticpoly(butene-1)(iPB)withsphericalmorphologywassynthesizedsuccessfullywithbulkprecipitationpolymerizationwithoutpost-treatmentoftheproducts.ThebulkprecipitationpolymerizationprocessmadeitpossibleforiPBtobeusedasgeneralplasticduetotheacceptabledecreasedcostcomparedwiththesolutionpolymerizationprocess.TheinfluenceofcatalystresiduesontheagingandthermalstabilityofiPBsynthesizedbybulkprecipitationpolymerizationmethodwasinvestigatedbygelpermeationchromatography,mechanicalperformancetesting,thermogravimetricanalysisandinfraredspectroscopicanalysis.CommercialiPBandthelab-madeiPBwithvariedcatalystresiduecontentswerestudied.TheresultsdemonstratedthatthecatalystresiduesplayedanimportantroleintheagingprocessoftheiPB.Apossiblemechanismofagingpromotionbycatalystresidueswasproposed.

简介：这篇论文在磁铁矿(Fe3O4)的弱磁性的帮助地的合成上论述试验性的结果在一个氧化一起沉淀方法的nano粒子，与没有磁性的正式就职的盒子相比。XRD结果证明在220G下面的弱磁性的正式就职能从goethite(α-FeOOH)加速阶段转变到磁铁矿(Fe3O4)，并且影响水晶结构，粒子尺寸/形态学和磁铁矿nano粒子的磁性的反应综合。另外，在合成反应的FeCl2答案的更高的集中导致了更好的粒子，有或没有磁性的正式就职。

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简介：CuO-CeO2catalystswerepreparedbyaureaprecipitationmethodfortheoxidativesteamreformingofethanolatlow-temperature.Thecatalyticperformancewasevaluatedandthecatalystswerecharacterizedbyinductivelycoupledplasmaatomicemissionspectroscopy,X-raydiffraction,temperature-programmedreduction,fieldemissionscanningelectronmicroscopyandthermo-gravimetricanalysis.OverCuOCeO2catalysts,H2withlowCOcontentwasproducedinthewholetestedtemperaturerangeof250–450C.Thenon-noblemetalcatalyst20CuCeshowedhigherH2productionratethan1%Rh/CeO2catalystat300–400Candtheadvantagewasmoreobviousafter20htestingat400C.TheseresultsfurtherconfirmedthatCuO-CeO2catalystsmaybesuitablecandidatesforlowtemperaturehydrogenproductionfromethanol.

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简介：Inthiswork,theinfluenceofCO2onthestructuralvariationandcatalyticperformanceofNa2WO4/Mn/SiO2foroxidativecouplingofmethanetoethylenewasinvestigated.ThecatalystwaspreparedbyimpregnationmethodandcharacterizedbyXRD,RamanandXPStechniques.AppropriateamountofCO2inthereactantgasesenhancedtheformationofsurfacetetrahedralNa2WO4speciesandpromotedthemigrationofOinMOx,Na,Wfromthecatalystbulktosurface,whichwerefavorableforoxidativecouplingofmethane.WhenthemolarratioofCH4/O2/CO2was3/1/2,enrichedsurfacetetrahedralNa2WO4speciesandhighsurfaceconcentrationofOinMOx,Na,Wweredetected,andthenhighCH4conversionof33.1%andhighC2H4selectivityof56.2%wereobtained.WithfurtherincreaseofCO2inthereagentgases,thecontentofactivesurfacetetrahedralNa2WO4speciesandsurfaceconcentrationofOinMOx,Na,Wdecreased,whilethatofinactivespecies(MnWO4andMn2O3)increaseddramatically,leadingtolowCH4conversionandlowC2H4selectivity.ItcouldbespeculatedthatNa2WO4crystalwastransformedintoMnWO4crystalwithexcessiveCO2addedunderthereactionconditions.PretreatmentofNa2WO4/Mn/SiO2catalystbymoderateamountofCO2beforeOCMalsopromotedtheformationofNa2WO4species.