哈爾濱理工大學(xué)學(xué)士學(xué)位論文哈爾濱理工大學(xué)學(xué)士學(xué)位論文#Methanolisoneofthelowmolecularweightalcoholsthoughttoactasanactivatorspeciesintheureaprocess.?Thepreseneeofmethanolisthoughttoincreasethesolubilityofureainthefuel,whichresultsinamorecompleteurea/alkanereactionandfasterreactiontimes.AlsoshowninFigure2istheDSCcurveforfueltreatedwithamixtureofureaandmethanol.Theaboveprocedurewasrepeatedwiththeadditionof1mLofmethanol.Thefigureshowsthattheurea/methanoltreatmenteliminatesthefreezingexothermoutbelow-65°C,providingashiftintheexothermpeakbymorethan10°C.Thisshowsthattheurea/methanoltreatmenthasthepotentialtoproducefuelthathasimprovedlow-temperaturepropertiesbeyondthatofin-specificationJPTS(seeFigure1forcomparison).Toconfirmthattheimprovedlow-temperaturebehaviorisduetotheremovalofnormalalkanes,asexpectedfrompreviousstudies,andtostudytheselectivityoftheprocessforvarioussizealkanes,weusedgaschromatography(GC)tomeasurethechangeinconcentrationofthenormalalkanesuponureatreatment.Figure3showsachromatogramofthe3219fuel,whichshowsthatthisfuelcontainsnormalalkanesprimarilyintherangeCtoC,withonlyverysmallamountsofC(<0.0591617mol%).Figure4showsthepercentdecreaseinconcentrationofthesenormalalkanesaftertheurea/methanoltreatmentdescribedabove.Thesmalleralkanes,CtoC,aredecreasedby10to25%.Thelargernormal913alkanes(>C)areremovedtothegreatestextent,withessentially100%14removalofn-C.Thisshowsthattheurea/methanoltreatmentprocessis16selectivetowardthelargernormalalkanespresentinjetfuel.Thisselectivitytowardlong-chainn-alkanesisquitedesirable,asthesespecieshavebeenimplicatedasbeingthefirstspeciestocrystallizeuponthecoolingofthesefuels.12_1Theinitialcrystallizationofthesespeciescausesfuelclouding,whichatlowertemperaturesand/orlongertimes,resultsinfuelgelationandtheinhibitionoffuelflow.Aprimarybenefitoftheurea哈爾濱理工大學(xué)學(xué)士學(xué)位論文哈爾濱理工大學(xué)學(xué)士學(xué)位論文哈爾濱理工大學(xué)學(xué)士學(xué)位論文哈爾濱理工大學(xué)學(xué)士學(xué)位論文adductionprocessisinthisselectivitytowardremovalofthespeciesthatformsolids(relativelylargenormalalkanes),whilebeingmuchlesslikelytoreactwithotherfuelspecies,suchasaromatics,branchedalkanes,andcycloalkanes(naphthenes).Also,theprocesssignificantlylowersthemeasuredfreeze,cloud,andpourpoints(seebelow),whiletheuseofcold-flow-improvingadditiveshasnotdemonstratedsignificantchangesinFigure3Chromatogramoffuel3219showingnormalalkanes.Figure4Plotofpercentdecreaseofvariousnormalalkanesafterurea/methanoltreatment.xcix哈爾濱理工大學(xué)學(xué)士學(xué)位論文哈爾濱理工大學(xué)學(xué)士學(xué)位論文哈爾濱理工大學(xué)學(xué)士學(xué)位論文哈爾濱理工大學(xué)學(xué)士學(xué)位論文附錄CCIM.s.密呂.紹s.i.ABlii.tw.u?-w.rBRs.Flic<=■UJ0三E?SIi$SH.-￡Eiw^Ei5E*wk=FIeax!*jfKfs!署加.啟宜鬲芒一奩貝川町tb-困醫(yī)■l-sprELH涇軌日吏0R134站里UImg曲r^.K.ss—sT7Ayh§org爼廬v蚤巧：.F「<」ITII—o1占1營邕拾240蚩fn.Enthalpy軒二閃一1]V、A\-fvCP崑tetjtug譽醬C