Trends in Auto Emissions and Gasoline Composition

8/14/2019 Trends in Auto Emissions and Gasoline Composition

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Brogan & Partners

Trends in Auto Emissions and Gasoline CompositionAuthor(s): Robert F. SawyerSource: Environmental Health Perspectives, Vol. 101, Supplement 6: Health Effects of Gasoline(Dec., 1993), pp. 5-12Published by: Brogan & PartnersStable URL: http://www.jstor.org/stable/4640351.

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EnvironmentalHealthPerspectivesSupplements101 Suppl.6):5-12 (1993)

r e n d s n u t o missions n d asolineomposition

y R o b e r t S a w y e rThe inventionof the spark-ignited nternal combustionengine provideda market for a petroleummiddledistillate, gasoline, about100years ago. The internal combustionengine and gasoline have co-evolveduntilmotorvehicles nowannuallyconsumeabout110billiongallonsof gasoline in the United States.Continuingairpollution problemsandresultingregulatorypressuresare drivingthe need for further automotiveemissions

reductions.Engine andemissions control echnologyprovidedmost earlierreductions.Changing he composi-tion of gasoline will play a major role in the next round of reductions.The engineering and regulatorydefinition of a reformulatedgasoline is proceedingrapidly, argelyas the result of an auto and oil industrycooperativedata generationprogram.It is likely that this new,reformulatedgasoline will be introduced nhigh-ozone regions of the United States in the mid-1990s.Alternative clean fuels, primarily methane,methanol,and liquid petroleumgas, will becomemorewidelyused duringthis sameperiod,probably irst infleet operations.

Historical ackgroundThe commercialdevelopment f petroleumduringthelast half of the nineteenthcenturywas motivatedby theneed for an inexpensive ubstituteforwhaleoil. Distilla-tion of crudepetroleum o producekerosenefor use as

lampoil left severalbyproducts or whichthere was nomarket,among hemgasoline.Thisdistillateprovedbettersuited thankerosene oruseinthethen-developingpark-ignitedinternalcombustionngine.The internalcombus-tion engine thereby provided a second market forpetroleumproductsand soonoutstripped he demand orlampoil. Theinternalcombustionngineandgasolineco-evolvedover henext 100years,withprimaryemphasisontheimprovementfpower, fficiency, nddrivability. eadwas added to gasoline in the 1930s to increase knockresistance, allowing higher compression ratios andgreater efficiency.The role of the automobilen air pollutionwas recog-nizedin the 1950s,and the first emissionscontrolswereinitiatedin the 1960s. These controls have focused pri-marily on the engine. They have revolutionized nginedesign,mostnotably hrough he introduction fcomputercontrol.The co-evolution fengineandfuelcontinued.Twoimportantfuel modifications ccurred:removalof leadfromgasolinealloweduse ofcatalyticaftertreatment, ndreductionof gasolinevaporpressureassisted in the con-trol of refuelingandevaporative ydrocarbon missions.

The emissionscontrols ntroduced n the 1970swererefined n the1980s.Most mportantly,he 1980sprovidedtime for the needed turnover of vehicles necessary tonearlyeliminateprecatalyst ehicles romthe motorvehi-cle fleet.Aswe enterthe1990s,hedisappointing eality sthat we are far from attaining air quality standards,especiallyin urbanareas, and motorvehiclesremainamajorpart of the problem. ncreasingnumbersof motorvehicles,milestraveled,andin-useemissions hat exceedregulatory expectations prevent the attainment ofexpected emissions reductions.An additionaleffort toreduce n-usemotorvehicleemissionsreductions s neces-sary.The co-evolution f enginesandfuels is continuing,but now the fuel is the focus of attention.

GasolineGasoline s a middledistillateof petroleum, ontainingC4 to about C12 hydrocarbons.Throughcatalytic andhydro cracking,modernrefineriesconvertheavy distil-latesofpetroleumntogasoline-blendingomponents.so-merizationand reformationare employedto use lightdistillatesas gasolinecomponents. racticallyallgasolineintheUnitedStates smade rompetroleum.Tar ands,oilshale,andcoal can be used as raw materials orgasoline,but they are not currentlyeconomically ompetitivewithcrudepetroleum.Becauseof the extensivegasolinemotorvehicle leet and the gasolineproduction nd distributioninfrastructure,t is likelythat gasolinewill be the domi-nant motorvehicle uel wellinto the nextcentury,evenas

petroleum eserves aredepleted.

1Mechanical ngineeringDepartment,Universityof CaliforniaatBerkeley,Berkeley,CA94720.Thismanuscript aspresented ttheInternationalymposiumn heHealthEffectsofGasoline eld5-8 November 991n Miami,FL.

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6 R. F. SAWYER

About 84%of the approximately30billiongallonsofmotor fuel consumedannually n the United States isgasoline 1).Thisgasoline raction s muchhigher han formost countriesnthe rest of theworld,wheredieselfuel smuch more widely used. The United States consumesabouthalf of the world's asoline.About2billiongallonsofoxygenates,primarily thanolandmethyl ert-butyl ther(MTBE), re added o U.S.gasoline.As fueleconomy nd/or global warmingconcerns ncrease,a shift to a higherdieselmotor uelfraction nthe UnitedStatesis likely,butgasolinewill remain he dominant uel.Regulatory ontext

The CleanAir Act amendments f 1990followearlierCleanAir Acts in setting technologyforcingemissionsstandards.Theyalsoestablisha clean uel programandrequirereformulatedgasoline. California's ight to setmore stringent requirementsand the option of otherstates that do not meet airqualitystandards o adopt heCaliforniamotorvehicle emissionstandards s retained.Theactionsofthe California irResourcesBoard CARB)therefore resignificant otonly n California ut n otherhigh-pollutiontatesas well.Emissions Regulations

Morestringent nationaltailpipeemissions standardsfor automobiles re to be phasedin overthe 1994-1996modelyears(Table ).Durability equirements re doubledto 10yearsor100,000miles.TheEPA s directed oimposea secondroundof strictertailpipe tandardsbeginning n2004 if needed, feasible, and cost effective.CARB hasestablished equirementsor owemission ehicles LEVs)includingzero-emission ehicles(ZEVs),whichare elec-tric vehicles(Table2).The EPAandCARBproposenewevaporative missiontest methods designed to greatlyreducethis sourceof hydrocarbon missions.AdditionalnewCleanAirActrequirementsncludea 10g/milecarbonmonoxideCO) tandardwhen estedat 20'F andonboarddiagnostics.Reformulated Gasolines

The CleanAir Act amendments equirereformulatedgasoline nthe ninecities that mostseriouslyexceedozoneairquality tandardsbeginningn1995.Thisreformulatedgasolinemustdecreasevolatileorganic ompoundsVOCs)by 15%.It must also reduce toxics (benzene, 1,3-butadiene,formaldehyde, acetaldehyde, and polycyclic organic mat-ter) by 15%in 1995 and 25% in 2000. A 2% year-roundoxygen content is required. (A 2.7%winter oxygen contentis required in cities out of CO attainment.) The EPAapproach is based primarily on air quality improvementequivalence among different gasoline formulations. Cali-fornia is pursuing its own reformulatedgasoline program,based primarily on fuel specifications (Table 3). The Cali-fornia LEVs would be certified on the California reformu-lated gasoline. Other states opting to receive Californiavehicles presumably would also adopt Californiareformu-lated gasoline, although this point is not clear.

Table1.U.S.passengercar emission standards,50,000miles,Clean Air Act amendmentsof 1990.Pollutant 1960a 1989 1994-1996 2004bHC,g/mile 10.6 0.41 0.25c 0.125cCO,g/mile 84.0 3.4 3.4 1.7NO,, g/mile 4.1 1.0 0.4 0.2EvaporatedHC,g/test 46.6 2.0 2.0d 2.0dAbbreviations: C,hydrocarbons; O,carbonmonoxide;NOx,nitro-genoxides.aprecontrol.bTobereviewed ythe administratorf the EPA.eNonmethanehydrocarbons.dNew est procedure.

Table2. CaliforniaAir ResourcesBoardpassengercarlow-emissionvehicle standards(g/mile).YearCategory effectivea NMOGb CO NOxCurrent 1991 0.39 7.0 0.401993Base 1993 0.25 3.4 0.40TLEV 1995 0.125 3.4 0.40LEV 1995 0.075 3.4 0.20ULEV 1995 0.040 1.7 0.20ZEV 1998 0.000 0.0 0.00

Abbreviations:MOG, onmethane rganicgas; CO,carbonmonox-ide;NOx,nitrogenoxides;TLEV,ransition ow emission ehicles;LEV,low-emissionehicles;ULEV,ultralow emissionvehicles;ZEV,zero-emission ehicles.aIncludesphase-in, .g.,10%ZEV n 2003.bStandardsreadjusted orthe photochemicaleactivityof the fuel,e.g.,methanolTLEVreactivityadjustmentactor s 0.41.

Table3. CaliforniaAir Resources Board proposedreformulatedgasoline specifications,producer imits.Property LimitaRVP,psi 7.0Sulfur,ppm 40Benzene,vol% 1.0Aromatics,ol% 25Olefins, ol% 6T-90,OF 300T-50,OF 210Oxygen,minimum eight% 1.8Oyxgen,maximum eight% 2.2Abbreviations:VP,Reidvaporpressure;T-90,90%distillation em-perature;T-50,50%distillationemperature.aAveragingoptionalso availablewith lower imits.

AlternativeFuelsThe Clean-Fuel-Vehiclerogramof the CleanAirActapplies o 22 areasand fleet operations.Startingin 1998,vehicles with 80%lower emissionsmust be purchased.Cleanfuels could be alternative uels such as methanol,naturalgas, or reformulated asoline.Beginning n 1996,theindustrymustprovide 50,000 lean-fuel ars and ighttrucksto California ndin 1999,300,000vehicles.Califor-nia,particularlyhe SouthCoastAirQualityManagementDistrict (2),has its ownprograms o promote he use ofalternativeuels (Table ).



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EMISSIONSAND GASOLINECOMPOSITION 7Table4. South CoastAir Quality ManagementDistrict air qualitymanagementplan clean fuels strategy:motorvehiclemilestraveledpenetrationassumptionsfor 2010 2).%Use

AlternativeVehicle lass Electric fuelsa Gasoline DieselPassengercars 17 33 50 0Light-dutyrucks 9 38 53 0Medium-dutyehicles 0 40 57 3Heavy-duty ehicles 0 24 29 47Urbanbases 30 70 0 0Locomotives 90 0 0 10

aAlternativefuels underconsiderationncludemethanol,iquidpetro-leumgas, andnaturalgas.

Reformulated asolineAs nowused,theterm reformulatedasoline eferstogasolineblendsdesignedto reduce emissions.That fuel

composition affects emissions was known by earlyresearchersanddevelopers f vehicleemissionscontrols.Koehlet al. (3)review tudies of the relationsbetween uelcompositionand emissions conductedover the past 30years.Current nterestis motivated,n part, by competi-tion fromcleanalternative uels suchas alcohols,naturalgas, andliquidpetroleum as.Auto/Oil Program

Three domesticautocompanies ndfourteenpetroleumcompanies stablisheda cooperative esting and researchprogram,heAuto/OilAirQuality mprovement esearchProgram AOP),o developdata onpotential mprovementin vehicle emissions and air quality from reformulatedgasoline,otheralternativeuels,and new automotiveech-nology.Older(1983-1985),urrent(1989),and prototypevehiclesare included.This $40-million rogram s by farthe mostcomprehensivendsystematic tudyofthe com-bined effects of fuel parameterson motor vehicle emis-sions. The resulting extensivedatabase,now about 160millionentries, is publiclyavailable.*Test results for amatrixof fuels,vehicles,andoperating onditions ncludeboth exhaustand evaporative missionsdata, includingextensivehydrocarbonpeciation 4-9).Emissions Reductions

The AOPvehicleemissionsdataare based on FederalTest Procedure esting of a range of vehiclesand fuels.ARCO used these data to guide its formulationof areformulateduel,EC-X(Table5),which s similar o theCARB reformulated asoline.ARCO selected this fuelfromseveraltested as beingthe most cost effective, ow-emissiongasolineto produce.This fuel,whentested in a

Table5. Industryaverageand ARCOEC-Xreformulatedgasoline (10).Property Industryaverage EC-XOctane R + M)/2 86.8 90.0RVP,psi 8.6 6.7Sulfur,ppm 349 41Benzene, ol% 1.0 0.7Aromatics,ol% 34.4 21.6Olefins, ol% 9.7 5.5T-90,OF 323 293MTBE,vol% 0.0 14.9Abbreviations:+ M,roadoctane+ motoroctane;RVP,Reidvaporpressure;T-90,90%distillationemperature;MTBE,methyl ert-butylether.

Table6.ARCOEC-Xreformulatedgasolineemissions reductions(10).Emission Change,%Totalhydrocarbons -31Nonmethanerganicgases -36Carbonmonoxide -26Oxidesof nitrogen -26Total oxics - 46Evaporativeydrocarbons - 35

fleet of 1990California ehicles,showedsignificantemis-sionsreductionsTable ).Themagnitude ndconsistencyof emissions eductions fchemical omponentss surpris-ing (10).Emissionsreductions,air quality improvements, ndregulatoryrequirementsndicate hat reformulated as-olinewillbe introducednthe 1990s.Presumablyt willbereauiredn,andallocatedo,areaswiththe greatestozoneair-quality roblems.Alternativeuels

Natural gas, methanol, iquid petroleum gas (LPG),ethanol,andhydrogenarethe mostlikelyalternativesasclean substitutes for gasoline.All are compatiblewithcurrentgasolineand/ordieselenginedesigns,withmodestmodifications. heir relativeattractivenessdependspri-marilyon their air-qualitymprovement otential,whichresults primarily rom lowerphotochemicaleactivities.Availability nd issues such as vehiclerange and safetyalso are of concern.Natural gas, methanol,and LPG are receiving thegreatest attention.Naturalgas is the cleanestand mostwidely available.Vehiclefueling,on-boardstorage, andrangelimitations houldnotimpede he substantialadop-tionof naturalgas as a motorfuel.Comparedo naturalgas, methanol s more like gasolinein its properties. tsproposeduse as a blendwith15% asoline M-85) ompro-mises emissions and air quality advantages comparedwith neat methanol(M-100),but solves cold start andsafety problems.Widespread ntroductionof methanolwould equiregreatlyexpanded roduction apability. heproduction f methanol romnaturalgas, the most likelyfeedstock,raises questionsof energy efficiencyandCO2emissions.LPGalready s widelyusedinternationallys a*Information n obtainingAuto/OilProgramresults, including hedatabaseon diskette,maybe obtainedby writingto the CoordinatingResearchCouncil, nc.,219 PerimeterCenterParkway,Atlanta,GA30346.



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8 R. F. SAWYER

motorfuel,but its availabilitys very limited.Ethanol swidelyused as a motor uel nBrazilbutdoes not offer heairqualityadvantagesofthe other uels.Lackof availabil-ityprecludes ydrogen, t eastuntilan nexpensive,nergy-efficient ource s discovered.

FuelVaporEmissionsThe emissions most directlyassociatedwith gasolineare fuel vaporemissions.These can be divided nto twocategories: torageand distribution missionsandvehicleevaporativemissions.Storage and Distribution Emissions

At eachpointwhere gasoline s storedor transferred,the potential for fuel vapors to escape exists. Duringstorage,fuelvaporpressure providesa drivingforce forthe escape of hydrocarbon apors,preferentially hosehaving the highest vapor pressures, the low molecularweight compounds.Cyclic warming of the fuel vapor,changesin barometric ressure,andwindpromotevaporemissions.Most storagetanks haveprovisions or mini-mizingemissions, uchas floatingroofsorvaporcollectionsystems.Whena tank s filledwithliquid,vapor s displaced nd,if notcollected, mitted o the atmosphere.Again, n mostregionswhere ozoneairquality s exceeded, hese vaporsarecollected,orexample, ythePhaseII VaporRecoverySystemsnow nstalledat many gasolinestations.If func-tioningproperly, hese systems effectivelycontrolemis-sionsto the atmosphere ndexposure o theperson illingthe automobileank.Vehicle EvaporativeEmissions

Fourrecognized ypes of vehicleevaporativemissionsare hot soak,diurnal,running osses, andresting losses.All are increasedby fuel vapor pressure, altitude,andambientemperature.Reduction f the fuelvaporpressureis an effectivemeans o reduceemissions.Thecompositionof these emissions s different romthe fuelcomposition.Evaporative missionsare enriched n the lowmolecularweight species.Eachtype of evaporativemissionhas itsown composition.Some examplespeciatedcompositionsareprovidedn the appendix.Hot soak emissionsoccur from the heatingof the fuelsystem after engineshutdown.These occurprimarily ncarbureted ehicles.Theincreasinguse of fuelinjectionsreducingthe importanceof the hot soak losses. Theseemissions,whenoccurringromvehiclesparkedn attachedresidential arages,contributeo indoor xposure.Diurnalemissions result from the cyclicheating andcoolingof the fuel tank. As the fuel and fuelvaporwarmand expand,diurnalemissions eave the tank. The char-coal canisterof the vehicleevaporative mission controlsystemis designed o trapthese emissionsand to deliverthemto theengine or destruction. f emissions xceed hecapacityof the canister,vaporsare emitted.Such emis-

sions canoccurand canbe aggravatedf the vehicle s notoperated.Thetemperaturedifference xperiencedby thefuel tankis animportantparameter.Running osses were recognizedas a source of hydro-carbonemissionsonlyabout2 years ago. In an extremecase,gasolinecan be heated o thepoint hat it boils nthefuel tank. Oncethe fuel boils, the evaporative missioncontrolsystemis overwhelmed, ndthe engine mayevenbe incapableof burningthe vaporized uel. Increasingengine temperatures,uel tank design and location,andfuel injection(whichheats and recirculatessome of thefuel) all haveincreasedthe severity of these emissions.Reducing uelvolatilitys aneffectivemitigationmeasure.Testmethodsandregulationsarebeingestablished.Restinglosses result fromthe diffusionof fuelthroughplasticandrubber uelsystem components ndthe escapeof hydrocarbon aporsfrom the storagecanister.Theseprocesses are not well understood.Whileemissionratesarelow, heyoccurcontinuouslynd ntotalcanbe signifi-cant.Theyare similar o hot soak emissions,but largelymissed in the 1-hrhot soak test. Measurementof theseemissions s difficult.The new Californiamultiday vap-orative est procedurebeginning n 1995willrequirecon-trol of these emissions. Speciated data are not yetavailable.ExhaustEmissions

Fuelcomposition ndmanyotherengineandoperatingparameters affect the pollutant composition of theexhaust.Typically, 9.5-99.9%of engine exhaustfrom amodern,ight-dutyvehicle s nitrogen,carbondioxide, ndwatervapor.The remainder ontains he pollutants.Mostimportant rehydrocarbons,ldehydes, arbonmonoxide,oxidesof nitrogen,andlead.Hydrocarbons

Exhausthydrocarbons an be raw fuel or modified ncomposition y the combustion rocess.The data in theappendix how that the hydrocarbon omposition f fuel,evaporativemissions, ndexhaustemissionsareall differ-ent.Theoperating ondition f the vehicle(coldstart,hotstabilized, r hotstart),also affectshydrocarbon omposi-tion.Unburnedgasolinecan pass throughthe engine (forexample, trapped in a crevice region) and catalyst(especiallyduringcoldstart).Someof the exhausthydro-carbonspecies thereforemimicthe compositionof theliquid uel.Pyrolysis products,which result from the high-tem-peraturecombustion nvironment nd the catalyticreac-tor,can be speciesnotpresent n the fuel.1,3-Butadienesanexampleof a hydrocarbonpeciesfound n the exhaustthat is not presentin the fuel.By monitoring he engineandtailpipe missions omposition,heroleofthe combus-tion andcatalystprocessescan be inferred.Such nforma-tion,which s being generatedby the AOP, s valuable ofuel,engine,and emissioncontroldesignei's.



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EMISSIONSAND GASOLINECOMPOSITION 9

OtherCompoundsAldehydes,carbonmonoxide,oxides of nitrogen,andlead are also important exhaust emissions. Each isaffectedby the composition f the gasoline.Aldehydes esultfrom hepartialoxidation fhydrocar-bons or can be formedfrom oxygenatedhydrocarbons

contained n the fuel. Methanoland MTBE as fuel addi-tives,forexample,generally ncrease ormaldehydemis-sions.Ethanolandethyltert-butyl ther(ETBE) ncreaseacetaldehyde missions.Carbonmonoxides an intermediaten the oxidation fhydrocarbons. he failure o fullyconvertcarbonmonox-ideto carbondioxide ccursprimarilyduringcoldstart orresults roman nsufficiencyfoxygenresulting rom uel-rich operation.A troublesome ecent observations thatsome vehiclesgo into a fuel-richoperatingmodeduringheavyacceleration.Oxidesof nitrogenfromgasolinevehicles result fromthe thermal ixationofatmospheric itrogen.Theprocessdependsstronglyonpeak temperature ndmixtureratio.The effectof fuelcomposition n oxidesof nitrogenemis-sions is complex ndnotfullyunderstood.Leademissionsarethedirectresultoflead added o fuelas an antiknock gent.Atmospheric ndhumanead evelshave allendramatically ith the introduction f unleadedgasolineand reductionof lead levels in leadedgasoline.With the completeelimination f leadfromgasoline, hisproblemwill be solved.Conclusions

Gasolineand the spark-ignition nginehave co-evolvedover hepast100years.Additional hangesareoccurring,drivenby the need to reduce urthermotorvehicleemis-sions.Gasoline ompositionnd autoemissionsarecloselyrelated.The mechanismof this relation s often complex,but new data areyieldinga betterunderstanding.Refor-mulatedgasolineresults in reducedemissions, s being

mandatedby regulatoryaction,and shouldbe introducedin the mid 1990s.This fuel will have a lower aromaticcontent(including pecificallybenzene), owerolefin con-tent,anoxygenateadditive,owervaporpressure,reducedsulfur content, and reduced high-end (high molecularweight)content.Alternative clean uels,primarilymeth-ane,methanol,andliquidpetroleumgas, also can reduceemissionsandare scheduled or ntroductiono fleetoper-ations.

REFERENCES1.U.S.DOE.TheMotorFuelConsumption odelThirteenthPeriodicalReport,DOE/OR/21400-H5, .S. Departmentof Energy,Wash-ington,DC,January1988.2. SouthCoastAirBasin.AirQualityManagement lan,SouthCoastAirQualityManagementDistrict,DiamondBar,CA,1989.3. Koehl,W.J.,Benson,J.D.,Burns,V.,Gorse,R.A.,Hochhauser, .M.,andReuter,R. M.Effectsofgasolinecompositionndpropertiesonvehicleemissions: reviewofpriorstudies.SAEPaperNo. 912321,SocietyofAutomotive ngineers,Warrendale,A,1991.4.Auto/OilAirQuality mprovement esearchProgram. nitialMassExhaustEmissionsResults romReformulated asolines.TechnicalBulletinNo.1, Coordinating esearchCouncil,Atlanta,GA,1990.5.Auto/OilAir QualityImprovementResearchProgram.Effects ofFuel SulfurLevelson Mass ExhaustEmissions.TechnicalBulletinNo.2, Coordinating esearchCouncil,Atlanta,GA,1991.6.Auto/OilAirQuality mprovement esearchProgram.Air QualityModelingResults for ReformulatedGasolines n Year 2005/2010.TechnicalBulletinNo. 3, Coordinating esearchCouncil,Atlanta,GA,1991.7.Auto/OilAirQuality mprovementesearchProgram.MassExhaustEmissionsResultsfrom Reformulated asolinesn OlderVehicles.TechnicalBulletinNo. 4, CoordinatingResearchCouncil,Atlanta,GA,1991.8.Auto/OilAir QualityImprovementResearchProgram.ExhaustEmissionsof ToxicAir PollutantsUsing ReformulatedGasolines.TechnicalBulletinNo. 5, Coordinating esearchCouncil,Atlanta,GA,1991.9.Auto/OilAir QualityImprovementResearchProgram.EmissionsResultsof OxygenatedGasolinesand Changes n RVP.TechnicalBulletinNo.6, 1991.10.ARCOProductsCompany. C-X Reformulated asolineTestPro-gramEmissionsData. CleanFuelsReport91-06.



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10 R. F. SAWYER

AppendixHydrocarbon ompositionof fuels and emissions:Hydrocarbon peciationof industry averagegasoline,EPAcertificationgasoline, and M-85(85%methanol,15% asoline).aFUELS EXHAUSTEMISSIONS EVAPORATIVEMISSIONS COMPSTE

Ind Cert M-85 Cold Hot Hot Diurnal Hot RunningAvg Gas Start Stab Start Soak LossesCAS# Compound Gas00074-82-8 Methane 0.000 0.000 0.000 0.0895 0.5446 0.2871 0.0078 0.0099 0.0084 0.155200074-85-1 Ethene 0.000 0.000 0.000 0.0790 0.0072 0.0522 0.0000 0.0000 0.0000 0.026900074-86-2 Ethyne 0.000 0.000 0.000 0.0376 0.0000 0.0000 0.0000 0.0000 0.0000 0.008700074-84-0 Ethane 0.000 0.000 0.000 0.0224 0.0411 0.0439 0.0006 0.0000 0.0000 0.018300050-00-0 Formaldehyde 0.000 0.000 0.000 0.0060 0.0298 0.0123 0.008000115-07-1 Propene 0.000 0.000 0.000 0.0397 0.0000 0.0101 0.0000 0.0000 0.0000 0.010700074-98-6 Propane 0.001 0.001 0.001 0.0000 0.0000 0.0000 0.0027 0.0004 0.0000 0.000400463-49-0 Propadiene 0.000 0.000 0.000 0.0013 0.0000 0.0000 0.0000 0.0000 0.0000 0.000300074-99-7 Propyne 0.000 0.000 0.000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000075-28-5 2M-Propane 0.083 0.086 0.016 0.0004 0.0000 0.0018 0.0230 0.0035 0.0231 0.009200075-07-0 Acetaldehyde 0.000 0.000 0.000 0.0035 0.0216 0.0071 0.005400115-11-7 2M-Propene 0.014 0.015 0.000 0.0176 0.0000 0.0000 0.0000 0.0000 0.0000 0.004100106-98-9 1-Butene 0.000 0.000 0.000 0.0034 0.0000 0.0000 0.0000 0.0000 0.0000 0.000800106-99-0 1,3-Butadiene 0.000 0.000 0.000 0.0068 0.0000 0.0000 0.0000 0.0000 0.0000 0.001600106-97-8 Butane 4.650 4.085 1.012 0.0349 0.0665 0.0931 0.5270 0.2116 0.7337 0.295300624-64-6 t-2-Butene 0.001 0.001 0.000 0.0038 0.0000 0.0000 0.0000 0.0000 0.0000 0.000900463-82-1 2,2-DM-Propane 0.034 0.067 0.000 0.0006 0.0000 0.0000 0.0004 0.0000 0.0019 0.000600107-00-6 1-Butyne 0.000 0.000 0.000 0.0000 0.0000 0.0000 0.0000 0.0033 0.0000 0.000300590-18-1 c-2-Butene 0.004 0.001 0.000 0.0016 0.0000 0.0023 0.0000 0.0006 0.0000 0.000800563-45-1 3M-1-Butene 0.021 0.016 0.000 0.0000 0.0000 0.0000 0.0003 0.0000 0.0000 0.000000064-17-5 Ethanol 0.000 0.000 0.000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000078-78-4 2M-Butane 4.417 2.306 0.567 0.0294 0.0458 0.0594 0.1030 0.0918 0.0888 0.066000503-17-3 2-Butyne 0.000 0.000 0.000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000109-67-1 1-Pentene 0.146 0.114 0.019 0.0008 0.0000 0.0000 0.0019 0.0016 0.0017 0.001000563-46-2 2M-1-Butene 0.319 0.244 0.042 0.0020 0.0000 0.0008 0.0060 0.0058 0.0030 0.002600109-66-0 Pentane 3.385 1.212 0.440 0.0219 0.0123 0.0364 0.0521 0.0669 0.0317 0.032900078-79-5 2M-1,3-Butadiene 0.013 0.003 0.001 0.0017 0.0000 0.0000 0.0000 0.0007 0.0000 0.000500646-04-8 t-2-Pentene 0.617 0.384 0.083 0.0037 0.0000 0.0000 0.0094 0.0124 0.0032 0.004000558-37-2 3,3-DM-1-Butene 0.010 0.002 0.001 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000002738-19-4 2M-2-Hexene 0.338 0.205 0.051 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000003899-36-3 3M-t-3-Hexene 0.000 0.000 0.000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000014686-13-6 t-2-Heptene 0.131 0.078 0.019 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000816-79-5 3E-c-2-Pentene 0.061 0.035 0.009 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000107-39-1 2,4,4-TM-1-Pentene 0.104 0.061 0.016 0.0000 0.0000 0.0000 0.0000 0.0004 0.0000 0.000010574-37-5 2,3-DM-2-Pentene 0.000 0.000 0.000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000006443-92-1 c-2-Heptene 0.121 0.073 0.018 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000108-87-2 M-Cyclohexane 0.542 0.285 0.081 0.0023 0.0000 0.0000 0.0000 0.0013 0.0000 0.000700590-73-8 2,2-DM-Hexane 0.063 0.032 0.008 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000107-40-4 2,4,4-TM-2-Pentene 0.011 0.000 0.000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000592-13-2 2,5-DM-Hexane 0.552 0.702 0.081 0.0034 0.0000 0.0000 0.0000 0.0011 0.0014 0.001201640-89-7 E-Cyclopentane 0.074 0.043 0.011 0.0005 0.0000 0.0000 0.0000 0.0000 0.0000 0.000100589-43-5 2,4-DM-Hexane 0.707 0.885 0.103 0.0051 0.0000 0.0009 0.0000 0.0014 0.0017 0.001800563-16-6 3,3-DM-Hexane 0.192 0.104 0.027 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000565-75-3 2,3,4-TM-Pentane 2.157 3.288 0.255 0.0129 0.0000 0.0082 0.0030 0.0083 0.0066 0.006900108-88-3 Toluene 5.518 6.743 0.934 0.0754 0.0347 0.0588 0.0470 0.1363 0.0109 0.052800584-94-1 2,3-DM-Hexane 0.539 0.575 0.078 0.0029 0.0000 0.0014 0.0000 0.0012 0.0000 0.001000592-27-8 2M-Heptane 0.931 0.505 0.130 0.0048 0.0000 0.0014 0.0000 0.0015 0.0000 0.001400589-53-7 4M-Heptane 0.462 0.268 0.063 0.0013 0.0000 0.0008 0.0000 0.0000 0.0000 0.000400589-81-1 3M-Heptane 1.187 0.642 0.165 0.0079 0.0000 0.0029 0.0008 0.0027 0.0000 0.002615890-40-1 lc,2t,3-TM-Cyclopentane 0.000 0.000 0.000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000638-04-0 c-1,3-DM-Cyclohexane 0.087 0.049 0.013 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000002207-04-7 t-1,4-DM-Cyclohexane 0.136 0.077 0.019 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000003522-94-9 2,2,5-TM-Hexane 0.519 0.642 0.081 0.0026 0.0000 0.0008 0.0000 0.0003 0.0000 0.000700111-66-0 1-Octene 0.075 0.041 0.011 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000014850-23-8 t-4-Octene 0.100 0.074 0.015 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000111-65-9 Octane 0.856 0.429 0.119 0.0050 0.0000 0.0012 0.0000 0.0019 0.0000 0.001513389-42-9 t-2-Octene 0.074 0.043 0.011 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000002207-03-6 t-1,3-DM-Cyclohexane 0.125 0.079 0.019 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000007642-04-8 c-2-Octene 0.037 0.021 0.007 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000001069-53-0 2,3,5-TM-Hexane 0.103 0.111 0.016 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000002213-23-2 2,4-DM-Heptane 0.171 0.103 0.025 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000002207-01-4 c-1,2-DM-Cyclohexane 0.148 0.093 0.023 0.0000 0.0000 0.0000 0.0035 0.0000 0.0000 0.0005

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EMISSIONSAND GASOLINECOMPOSITION 11

Appendix.Continued.FUELS EXHAUSTEMISSIONS EVAPORATIVEMISSIONS COMPSTEInd Cert M-85 Cold Hot Hot Diurnal Hot RunningAvg Gas Start Stab Start Soak LossesCAS# Compound Gas01678-91-7 E-Cyclohexane 0.119 0.065 0.019 0.0000 0.0000 0.0000 0.0005 0.0019 0.0000 0.000200926-82-9 3,5-DM-Heptane 0.290 0.174 0.041 0.0003 0.0000 0.0000 0.0000 0.0009 0.0000 0.000100100-41-4 E-Benzene 3.283 1.989 0.498 0.0289 0.0000 0.0151 0.0084 0.0247 0.0000 0.012203074-71-3 2,3-DM-Heptane 0.073 0.048 0.012 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000108-38-3 m&p-Xylene 7.537 4.703 1.177 0.0709 0.0072 0.0323 0.0211 0.0584 0.0000 0.030402216-34-4 4M-Octane 0.426 0.215 0.059 0.0036 0.0000 0.0009 0.0000 0.0000 0.0000 0.001002216-33-3 3M-Octane 0.406 0.208 0.058 0.0021 0.0000 0.0000 0.0000 0.0000 0.0000 0.000500100-42-5 Styrene 0.091 0.066 0.014 0.0056 0.0000 0.0000 0.0000 0.0000 0.0000 0.001300095-47-6 o-Xylene 2.691 1.710 0.420 0.0245 0.0000 0.0104 0.0062 0.0206 0.0000 0.009900124-11-8 1-Nonene 0.105 0.119 0.016 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000627-20-3 c-2-Pentene 0.358 0.218 0.049 0.0007 0.0000 0.0000 0.0050 0.0057 0.0018 0.001800513-35-9 2M-2-Butene 1.032 0.617 0.142 0.0063 0.0000 0.0013 0.0167 0.0199 0.0047 0.006800542-92-7 Cyclopentadiene 0.003 0.002 0.000 0.0008 0.0000 0.0000 0.0000 0.0000 0.0000 0.000200075-83-2 2,2-DM-Butane 1.057 0.114 0.142 0.0084 0.0000 0.0058 0.0090 0.0103 0.0026 0.005600142-29-0 Cyclopentene 0.153 0.091 0.021 0.0000 0.0000 0.0000 0.0002 0.0010 0.0000 0.000100691-37-2 4M-1-Pentene 0.000 0.000 0.000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000760-20-3 3M-1-Pentene 0.120 0.072 0.017 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000287-92-3 Cyclopentane 0.208 0.111 0.030 0.0003 0.0000 0.0000 0.0014 0.0018 0.0000 0.000400079-29-8 2,3-DM-Butane 1.621 0.689 0.224 0.0104 0.0000 0.0098 0.0099 0.0158 0.0052 0.007801634-04-4 MTBE 0.000 0.000 0.000 0.0000 0.0000 0.0000 0.0019 0.0049 0.0000 0.000700691-38-3 4M-c-2-Pentene 0.000 0.000 0.000 0.0000 0.0000 0.0000 0.0000 0.0019 0.0000 0.000200107-83-5 2M-Pentane 4.870 1.537 0.675 0.0298 0.0127 0.0381 0.0315 0.0564 0.0181 0.028100674-76-0 4M-t-2-Pentene 0.132 0.081 0.018 0.0000 0.0000 0.0000 0.0000 0.0004 0.0000 0.000000096-14-0 3M-Pentane 2.422 0.975 0.338 0.0155 0.0044 0.0178 0.0147 0.0257 0.0071 0.012800763-29-1 2M-1-Pentene 0.237 0.141 0.036 0.0000 0.0000 0.0000 0.0000 0.0015 0.0000 0.000100592-41-6 1-Hexene 0.109 0.064 0.015 0.0000 0.0000 0.0000 0.0007 0.0006 0.0000 0.000100110-54-3 Hexane 2.457 0.697 0.343 0.0150 0.0059 0.0174 0.0138 0.0248 0.0051 0.012213269-52-8 t-3-Hexene 0.225 0.133 0.032 0.0000 0.0000 0.0000 0.0000 0.0005 0.0000 0.000007642-09-3 c-3-Hexene 0.000 0.000 0.000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000004050-45-7 t-2-Hexene 0.337 0.200 0.048 0.0002 0.0000 0.0000 0.0000 0.0012 0.0000 0.000200616-12-6 3M-t-2-Pentene 0.280 0.165 0.040 0.0011 0.0000 0.0000 0.0005 0.0024 0.0000 0.000500625-27-4 2M-2-Pentene 0.316 0.188 0.046 0.0000 0.0000 0.0000 0.0000 0.0010 0.0000 0.000101120-62-3 3M-Cyclopentene 0.313 0.217 0.053 0.0000 0.0000 0.0000 0.0034 0.0079 0.0010 0.001407688-21-3 c-2-Hexene 0.186 0.110 0.026 0.0000 0.0000 0.0000 0.0000 0.0004 0.0000 0.000000637-92-3 ETBE 0.000 0.000 0.000 0.0005 0.0000 0.0000 0.0003 0.0024 0.0000 0.000400590-35-2 2,2-DM-Pentane 0.344 0.203 0.051 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000096-37-7 M-Cyclopentane 0.957 0.481 0.138 0.0066 0.0000 0.0047 0.0048 0.0096 0.0000 0.003700108-08-7 2,4-DM-Pentane 0.974 1.464 0.143 0.0069 0.0000 0.0051 0.0028 0.0044 0.0032 0.003900464-06-2 2,2,3-TM-Butane 0.023 0.022 0.001 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000071-43-2 Benzene 1.776 0.689 0.300 0.0494 0.0459 0.0553 0.0192 0.0447 0.0058 0.034903404-61-3 3M-1-Hexene 0.022 0.007 0.002 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000562-49-2 3,3-DM-Pentane 0.104 0.067 0.015 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000110-82-7 Cyclohexane 0.195 0.079 0.028 0.0002 0.0000 0.0000 0.0000 0.0004 0.0000 0.000100591-76-4 2M-Hexane 1.478 1.923 0.211 0.0089 0.0000 0.0045 0.0039 0.0077 0.0020 0.004400565-59-3 2,3-DM-Pentane 1.478 1.923 0.211 0.0100 0.0000 0.0085 0.0046 0.0077 0.0046 0.005900110-83-8 Cyclohexene 0.026 0.015 0.004 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000589-34-4 3M-Hexane 1.397 0.874 0.203 0.0100 0.0000 0.0076 0.0045 0.0078 0.0018 0.005102532-58-3 c-1,3-DM-Cyclopentane 0.311 0.155 0.046 0.0004 0.0000 0.0000 0.0000 0.0004 0.0000 0.000100822-50-4 t-1,2-DM-Cyclopentane 0.426 0.244 0.061 0.0012 0.0000 0.0000 0.0000 0.0006 0.0000 0.000300592-76-7 1-Heptene 0.000 0.000 0.000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000540-84-1 2,2,4-TM-Pentane 3.341 4.700 0.481 0.0249 0.0246 0.0330 0.0164 0.0208 0.0200 0.0233

14686-14-7 t-3-Heptene 0.095 0.042 0.014 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000142-82-5 Heptane 1.168 0.576 0.169 0.0065 0.0000 0.0043 0.0012 0.0052 0.0010 0.003000111-84-2 Nonane 0.280 0.175 0.042 0.0004 0.0000 0.0000 0.0000 0.0000 0.0000 0.000100098-82-8 i-PropBenzene 0.139 0.091 0.022 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000015869-87-1 2,2-DM-Octane 0.090 0.099 0.013 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000100-52-7 Benzaldehyde 0.037 0.023 0.006 0.0011 0.0000 0.0000 0.000304032-94-4 2,4-DM-Octane 0.158 0.112 0.025 0.0039 0.0000 0.0014 0.0000 0.0015 0.0000 0.001200103-65-1 n-PropBenzene 0.713 0.441 0.111 0.0046 0.0000 0.0000 0.0000 0.0008 0.0000 0.001100620-14-4 1M-3E-Benzene 2.116 1.290 0.320 0.0192 0.0000 0.0054 0.0018 0.0100 0.0000 0.006400622-96-8 1M-4E-Benzene 0.924 0.566 0.140 0.0085 0.0000 0.0010 0.0006 0.0023 0.0000 0.002400108-67-8 1,3,5-TM-Benzene 1.092 0.663 0.168 0.0088 0.0000 0.0012 0.0000 0.0018 0.0000 0.002400611-14-3 1E-2M-Benzene 0.751 0.444 0.117 0.0068 0.0000 0.0010 0.0000 0.0009 0.0000 0.001800095-63-6 1,2,4-TM-Benzene 2.912 1.768 0.441 0.0232 0.0000 0.0055 0.0034 0.0114 0.0000 0.007700124-18-5 Decane 0.128 0.091 0.017 0.0005 0.0000 0.0000 0.0000 0.0000 0.0000 0.0001(Continued nnextpage)



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12 R. F SAWYERAppendix.Continued.FUELS EXHAUSTEMISSIONS EVAPORATIVEMISSIONS COMPSTE

Ind Cert M-85 Cold Hot Hot Diurnal Hot RunningAvg Gas Start Stab Start Soak LossesCAS# Compound Gas00135-98-8 s-ButBenzene 0.073 0.061 0.011 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.000005161-04-6 1M-4-i-ButBenzene 0.027 0.022 0.001 0.0000 0.0000 0.0016 0.0000 0.0000 0.0000 0.000200576-73-8 1,2,3-TM-Benzene 0.612 0.389 0.088 0.0047 0.0000 0.0000 0.0000 0.0005 0.0000 0.001100496-11-7 Indan 0.399 0.233 0.057 0.0017 0.0000 0.0000 0.0000 0.0000 0.0000 0.000400141-93-5 1,3-DE-Benzene 0.263 0.183 0.036 0.0002 0.0000 0.0000 0.0000 0.0000 0.0000 0.000100105-05-5 1,4-DE-Benzene 0.105 0.065 0.015 0.0019 0.0000 0.0000 0.0000 0.0000 0.0000 0.000400104-51-8 n-ButBenzene 0.608 0.377 0.086 0.0063 0.0000 0.0000 0.0000 0.0000 0.0000 0.001500135-01-3 1,2-DE-Benzene 0.270 0.178 0.037 0.0004 0.0000 0.0000 0.0000 0.0000 0.0000 0.000101120-21-4 Undecane 0.092 0.063 0.015 0.0014 0.0000 0.0000 0.0000 0.0000 0.0000 0.000300095-93-2 1,2,4,5-TetM-Benzene 0.254 0.156 0.037 0.0002 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000527-53-7 1,2,3,5-TetM-Benzene 0.353 0.222 0.050 0.0010 0.0000 0.0000 0.0000 0.0000 0.0000 0.000200488-23-3 1,2,3,4-TetM-Benzene 0.223 0.139 0.033 0.0002 0.0000 0.0000 0.0000 0.0000 0.0000 0.000000091-20-3 Naphthalene 0.476 0.301 0.073 0.0032 0.0000 0.0000 0.0000 0.0000 0.0000 0.000700112-40-3 Dodecane 0.111 0.071 0.016 0.0031 0.0000 0.0000 0.0000 0.0000 0.0000 0.000700067-56-1 Methanol 0.000 0.000 85.03400107-02-8 Acrolein 0.0012 0.0012 0.0000 0.000500067-64-1 Acetone 0.0025 0.0286 0.0094 0.006600123-38-6 Propionaldehyde 0.0004 0.0053 0.0011 0.001100123-73-9 Crotonaldehyde 0.0004 0.0029 0.0023 0.000900123-72-8 n-Butyraldehyde 0.0004 0.0001 0.0000 0.000100078-93-3 Butanone 0.0005 0.0079 0.0003 0.001500110-62-3 Pentanaldehyde 0.0000 0.0000 0.0000 0.000000104-87-0 p-Tolualdehyde 0.0005 0.0103 0.0046 0.002500066-25-1 Hexanaldehyde 0.0000 0.0000 0.0000 0.0000TOTAL 88.638 92.256 98.313 0.9888 0.9606 0.9896 0.9969 0.9964 1.0001 0.9883

aExampleailpipe,evaporative,ndcompositehydrocarbonmissions peciation singindustryaveragegasolineandprojected or a light-dutyvehicle leet for a given ocation ndfutureyear.Dataadapted rom heAuto/OilProgramdatabase.

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Trends in Auto Emissions and Gasoline Composition

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