Effects of different mixing ratios on emissions from passenger cars fueled with methanol/gasoline bl

Available online at www.sciencedirect.comJOURNAL OFENVIRONMENTAL中ScienceDirectSCIENCESISSN 1001-0742Joumal of Environmental Sciences 2011, 23(11) 1831-1838www.jesc.ac.cnLEL:Effects of different mixing ratios on emissions from passenger cars fueled withmethanol/gasoline blendsHong Zhaol'2, Yunshan Ge',;, Jianwei Tan', Hang Yinl3, Jiadong Guo', Wei Zhao', Peipei DailI. National Lab of Auto Performance & Emission Test, Beijing Instiute of Technology Bejing 100081, China. E-mail:qdlizh@ 163.com2. College of Mechanical & Electroric Engineering, Qingdao University, Qingdao 266071, China3. The Chinese Research Academy of Environmental Science, Beijing 100012, ChinaReceived 16 December 2010; revised 15 April 2011; accepted 18 April 2011AbstractRegulated and unregulated emissions from four passenger cars fueled with methanol/gasoline blends at diferent mixing ratios (M15,M20, M30, M50, M85 and M100) were tested over the New European Driving Cycle (NEDC). Volatile organic compounds (VOCs)were sampled by Tenax TA and analyzed by thermal desorption gas chromatograph/mass spectrometer (TD-GC/MS). Carbonylswere trapped on dinitrophenylhydrazine (DNPH) cartridges and analyzed by high performance liquid chromatography (HPLC). Theresults showed that total emissions of VOCs and BTEX (benzene, toluene, ethylbenzene, p, m, o-xylene) from all vehicles fucled withmethanolgasoline blends were lower than those from vehicles fueled with only gasoline. Compared to the basetine, the use of M85decreased BTEX emissions by 97.4%, while the use of M15 decreased it by 19.7%. At low-to-middle mixing ratios (M15, M20,M30 and M50), formaldehyde emissions showed a slight increase while those of high mixing ratios (M85 and M100) were threetimes compared with the baseline gasoline only. When the vehicles were retrofited with new three-way catalytic converters (TWC),emissions of carbon monoxide (CO), total hydrocarbon (THC), and nitrogen oxides (NOx) were decreased by 24%- -50%, 10%- -35%,and 24%- -58% respectively, compared with the cars using the original equipment manufacture (OEM) TWC. Using the new TwC,emissions of formaldehyde and BTEX were decreased, while those of other carbonyl increased. It is necessary that vehicles fueledwith methanol/gasoline blends be retroftted with a new TWC. In addition, the specific reactivity of emissions of vehicles fueled withM15 and reroftted with the new TWC was reduced from 4.51 to 4.08 compared to the baseline vehicle. This indicates that the use ofmethanol/gasoline blend at a low mixing ratio may have lower effect on environment than gasoline.Key words: mixing ratio; methanol/gasoline blend; BTEX; carbonyl compounds; new three way catalytic converterDOI:10.1016/S 1001-0742(10)60626-2Citation: ZhaoH ,Ge YS, TanJ w, Yin H, GuoJ D, Zhao W, Dai P P, 2011. Effects of diferent mixing ratios on emissions frompassenger cars fueled with methanolgasoline blends. Joumal of Environmental Sciences, 23(11): 1831-1838Introductionthe most widely investigated fuels. Methanol (CH3OH)has many advantages, which has made it an attractiveIn recent years, the dual worldwide crises of fossilnon-petroleum-based altemative fuel for the automotivefuel depletion and environmental degradation have posedindustry in many countries (Abu-zaid et al, 2004; Zervasincreasingly enormous threats to humans. To mitigate theseet al, 2002).threats from vehicles, many countries have made variousMethanol can be easily synthesized from natural gasefforts such as fuel quality improvement and introduction or from gasif.cation of coal or biomass (Kumabe eof exhaust aftertreatment technologies (Biswas et al, 2009;al., 2008). It has excellent combustion properties, lowZhao et al, 2010; Jiang et al, 2010). The developmentemission characteristics and improved engine power andof altemnative fuels to reduce automotive emissions andthermal eficiency. Methanol is more suitable for sparkprovide energy independence is becoming more impor-ignition engines because it has a low boiling point andtant, especially following the increased public attentionhigh octane number (da Silva et al., 2005). The highon energy securty and environmental pollution (Tang octane number allows methanol engines to have muchet al, 2007). Compressed natural gas, alcohols (ethanol higher compression ratios, thereby increasing thermal ef-and methanol), biodiesel and other fuels have been usedficiency. In mq”中国煤化工as the amountas altermative fuels (Kado et al, 2005; Agarwal, 2007; of methanolEnber increases.Zhang et al, 2009a; Lapuerta et al., 2008; He et al，Compared witTYHCNMHGnyandthermal2010). Among these alternative fuels, methanol is one ofefficiency are improved. When a gasoline engine is fueledwith a methanol/gasoline blend, few modifications to the$ Corresponding author. E-mail: geyunshan@bit.edu.cnNo. 11Effects of different mixing ratios on emissions from passenger cars fueled with methanol/gasoline blends1833mL/min using a Tenax TA sorbent tube. Tenax samplesentire test cycle. Compared to the baseline cars fueled onlywere analyzed by the thermal desorption preconcentrationwith gasoline, CO and THC emissions from cars fueledmethod, followed by identification by high resolutionwith methanol/gasoline blends were decreased by 11%-gas chromatography with a mass spectrometer detector34% and 10%- 49%, respectively, while NOx emissions(GC/MS). The thermal desorption system (Marks, UK) haswere increased by 53%- 474%. The decreases in THC andtwo stages of desorption. At the first stage the analytesCo emissions from vehicles fueled with methanol/gasolinewere desorbed with nitrogen flow from a sample tube thenblends are consistent with results reported by Liu et al.refocused onto a cold trap kept at -10°C. The second stage(2007) and Liao et al. (2006). The reduction in CO is .was a trap heated at 280°C to release materials into thedue to the fact that methanol contains only about 37.5%gas chromatograph capillary column (HP-5MS; 30 m xcarbon, while gasoline contains 85.8% carbon. This carbon0.25 mm ID, film thickness: 0.25 μm). The column wasconverts directly to CO during combustion, so the COkept isothermal at 35°C for 5 min and then heated upformation and emissions are quantitatively reduced whento 280°C at a rate of 5°C/min. Subsequently, the columnusing methanol. Moreover, methanol has a high oxygentemperature was kept at 280°C for 10 min. The MS wascontent (50 wt.%). When methanol is added into gasoline,run in SCAN mode with mass of 35- 550 amu. VOCs werethe methanol/gasoline blend contains more oxygen. Thisidentified by comparing mass spectra with those contained“pre-mixed oxygen efect" enables the reaction go to ain the NIST library and quantified by comparing areamore complete state, thus reducing CO and THC emissionsresponse with those of standard compounds using the ex-(Hu et al, 2007). The increase in NOx emissions is duetemal standard technique. The standard mixture of VOCsto the fast flame propagation speed and the enhanced(SEPA, China) contains benzene, toluene, ethylbenzene,combustion temperature.p-xylene, m-xylene, o-xylene, styrene, n-butylacetate andFor all the cars, most of the Co was produced duringn-undecane. Due to difficulties in resolving the chromatog-the first ECE cycle. In this stage, rich mixtures duringraphy peaks, the results for m-xylene and p-xylene areacceleration resulted in more engine-out CO. Simultane-represented as a sum.ously, the TWC had not reached the light of temperatureCarbonyl compounds in the dilution tunnel were sam-and was not able to function effectively. Therefore, thepled through a battery-operated air pump at a flowemission reductions were diminished. Generally speaking,rate of 1200 mL/min using a 2,4-dinitrophenylhydrazinefor CO emissions, the contribution to total emissions from(DNPH)-coated silica cartridge (Supelco, USA). Thethe first ECE cycle in methanol/gasoline-fueled cars wasreacted with DNPH togreater than that in gasoline fueled cars, which alwaysdrazones derivatives and were trapped. After elution andwere over 90%. Furthermore, the catalysts used withpretreatment, the final solution was analyzed by high-the methanol/gasoline fueled engines have longer light-performance liquid chromatography (HPLC, Agilent 1200,off times because of the lower exhaust temperatures asUSA) using ultraviolet detection at 360 nm. A 4.6x 150compared to gasoline-fueled engines. However, beginningmm Eclipse XDB C18 column (Agilent, USA) was used.with the second ECE and through the EUDC cycle, theA mixture of 60% acetonitrile and 40% water was usedTWC had fully warmed, thus the co emissions decreasedas mobile phases. Carbonyls were identified and quantifiedgreatly. The THC emissions showed a similar trend, butby comparison of their retention time and area responsewere not as prominent as Co emissions.to those of the standard compounds using the externalIn addition, cars that were fueled with low-to-middlestandard technique. The standard mixture (Supelco, USA)mixing ratio blends of methanol/gasoline were easy tocontains 14 components, namely, formaldehyde, acetalde-start. However, for M85 and M 100-fueled vehicles, morehyde, acrolein, acetone, propionaldehyde, crotonaldehyde,fuel had to be injected into the engine to start the vehicle.methyl ethyl ketone, methacrolein, butyraldehyde, ben-This rich mixture condition lasted for a long time inzaldehyde, valeraldehyde, tolualdehyde, cyclohexanonehe first ECE cycle, thus emitting more CO and THC.and hexanaldehyde. Because the column used cannot sep-Therefore, when the cars were fueled with low-to-middlearate acrolein and acetone, they were quantified together.mixing ratio blends of methanol/gasoline (M15, M20, M30The five-point external standard methods were used toand M50), the higher the mixing ratio, the lower themake linear calibration curve for quantification of VOCsTHC and CO emissions. When the cars were fueled withand carbonyl compounds. The correlation cofficients werehigh mixing ratio blends (M85 and M100), the THC andmore than 99.9%. VOCs and carbonyls of ambient airCo emissions were higher than those fueled with low-to-were sampled and analyzed in the same way as those frommiddle mixing ratio blends.the vehicle emissions. The effects of ambient air were allVehicles fueled with methanol/gasoline blends emittedsubtracted from the final results.low NOx in the ECE cycles because the temperature ofthe engine cylinder was not high enough to produce NOx.2 Results and discussionNOx emissions reached a maximum value in the EUDCcycle, during which 60%- 70% of total NOx were emitted2.1 Regulated emissionsfrom M15, M中国煤化工s. For the wholeFigure 2 presents the regulated emissions results as wellNEDC cycle,lYHCNMH Gol blended intoas relative emissions contributions from each stage of thegasoline resulcu h lngc NUA Cllisiuls.No. 11Effects of dfferent mixing ratios on emissions from passenger cars fueled with methanol/gasoline blends1835Table 1 VOC emision factors for diferent mixing ratis of methano/gasoline fueled vehicles (unit: mg/km)Vehicle 1Vehicle 2Vehicle 3Vehicle 4Gasoline M15GasolineMSOGasoline M85Gasoline M100Benzene0.4340.4971.6581.0301.2081.0604150.0320.8480.202Toluene1.5591.2317.5944.3384.9632.3754.9570.1521.875 ;0.588n- Butylacetate0.0210.0180.0100.0370.0340.0140.015Ethylbenzene0.3350.2172.3960.8030.3191.3130.0260.4020.110.p.m-Xylene0.4810.3422.4291.0880.9520.4481.7550.0590.5770.160Sturene0.0890.3520.2710.1300.099).4010.0130.1160.020o-Xylene0.3800.2741.9510.8660.7550.3941.620.0440.4390.129n-Undecane0. .0280.0470.0350.0160.0080.009Total VOCs3.3272.63116.4898.5938.8834.73912.512.0.3484.3151.233emissions are reduced when the cars are fueled within the increase of total carbonyls with the exception ofmethanol/gasoline blends.M20, which showed no obvious change from the baseline.Although M20, M30 and M50 were all tested on Vehicle2.3 CarbonyI compound emissions2, the category and quantity of additives of the threeCarbonyl compound emission factors from vehiclesfuels were different, which resulted in the total carbonylsfueled with methanol/gasoline blends at different mixing emitted from M50 being slightly higher than that fromratios are presented in Table 2. Formaldehyde emissions M20 but significantly lower than that from M30.were the most abundant carbonyl for all methanol/gasoline2.4 Eftects of new TWC on emissionsblends followed by acetaldehyde, acrolein+ acetone, ben-zaldehyde, and propionaldehyde. Formaldehyde can beFormaldehyde emissions are always a barrier to theproduced from alcohols and parafin, but the generation development of methanol/gasoline blend vehicles. Newof formaldehyde from methanol oxidation is easier thanTWCs were designed respectively for M15, M85 andfrom hydrocarbons, which results in higher formaldehyde M 100-fueled vehicles with the main aim of reducingemissions from engines fueled with methanol/gasoline formaldehyde emissions. Figure 3 shows comparisonsblends as compared with baseline gasline- fueled engines.between emissions of regulated emissions, BTEX andcarbonyls between vehicles ftted with the OEM TwC andconcentrations also increased. Similar results were also the new TWC for M15, M85 and M100-fueled vehicles,obtained by Zervas et al. (2002) and Wei et al. (2009). respectively. Retrofitted with the new TWCs, CO, THC,Moreover, Wei et al. (2009) found that formaldehydeand NOx were decreased by 24% -50%, 10%- -35%, andemission characteristics are approximately linear to the 24%- -58% respectively as compared with vehicles fttedamount of cyclic-supplied fuel methanol. In our study, with OEM TWC for methanolgasoline blends.with low-to-middle ratio methanol/gasoline blends (M15,Although the main aim of the new TWCs was to reduceM20, M30 and M50), formaldehyde emissions had a slightformaldehyde emissions, they also affected other regulatedincrease compared with the baseline, while that of high and unregulated emissions. With the use of the new TWC,ratio blends (M85 and M100) were three times higher thanformaldehyde emissions were decreased from 1.89 to 0.60the baseline.mg/km for M15, from 5.96 to 4.97 mg/km for M85 andHowever, there was a decrease in acetaldehyde from 5.73 to 3.79 mg/km for M100. All BTEX alsoemissions of 13%- -65% with different ratios of decreased to some extent, though other carbonyls such asmethanol/gasoline blends. In the case of other carbonyls,acetaldehyde and acrolein+ acetone showed an increase.there was an increase or decrease more or less. The sharpVOCs and cabonyls are also important precursors ofincrease in formaldehyde emissions eventually resulted photochemically-formed secondary pollutants, such asTable 2 Carbonyl compound emision factors for diferent mixing ratios of methanol/gasoline fueled vehicles (unit: mg/km)jasolineM1SasolineM20M30M50M85 GasolineM100Formaldehyde1.4961.878 2.9183.2705.0455.182 2.1405.9561.7845.348Acetaldehyde0.3860.317 2.6282.1481.5041.3190.9540.7610.268Acrolein + Acetone 0.2410.263 0.8210.6140.684 0.541 0.6960.4600.4740.181Propionaldehyde0.076 0.3990.2660.2470.210 0.2120.2070.1410.076Crotonaldehyde0.016 0.0490.0750.052Methyl ethyl ketone 0.2160.5070.3470.2640.1230.068Methacrolein0.159 0.3030.2810.1500.039Butyraldehyde0.4980.4800.074Benzaldehyde0.1330.138 0.1810.105n 320n 2580.121Valeraldehyde0.020 0.1030.053中国煤化工TolualdehydeCyclohexanone"MYHCNMHG.Hexanaldehyde0.080Total carbonyls2.5632.9487.9007.1129.0297.9565.4828.2813.6306.162.1836Jourmal of Environmental Sciences 201 I, 23(11) 1831-1838 1 Hong Zhao el al.Vol. 23.2厂0-幽co凼THC9 0.8-日NOx0.6-复0.4-0.2FkxxVeh1-M15Veh3-M85Veh3-M85NTVeh4-M100Veh4-M100NTtMI5 with OEM TWC日M15 with new TWC后0.Ls1|1!11|11lIIIM85 with OEM TWC口M8S with new TWC用。食1111111111111d四M100 with OEM TWC冒4to M100 with new TWCFig 3 Regulated emissions, BTEX and carbonyls comparison between OEM TWC and new TWC for MI5, M85 and M100 respectively. (a) regulatedermissions; (b) M15; (c) M85; (d) M100.ozone, which poses a serious air pollution problem un-(7.15 and 7.64 respectively). With the new TWC, emis-der specific summertime conditions. Since the individualsions of formaldehyde and p,m-xylene decreased sharplyVOCs and carbonyls react with diferent rates and difer-and their relative contributions to ozone forming poten-ent mechanisms, they also differ in their contribution totial were lowered. This leads to the conclusion that thephotochemical ozone formation (Schmitz et al, 2000).use of methanol/gasoline blends with the new TWC isIn the case of the use of new TWC, the specificfriendlier to the environment. When a gasoline vehiclereactivity was reduced from 4.84 to 4.08, from 6.14is modifed中国煤化工d vehicle, itisto 5.98, and from 6.22 to 6.14 for M15, M85 andnecessary toWC. Moreover,M100, respectively. Formaldehyde and p,m-xylene alsowhen an M1MYHC NMH Gd with the newhave the highest maximum incremental reactivity (MIR)TWC, its SR is lowered (from 4.51 to 4.08) compared.No. 11Effects of diferent mixing ratios on emissions from passenger cars fueled with methanol/gasoline blends1837with its gasoline counterpart with OEM TWC. For lowment, 43(11): 1917-1925.mixing ratio methanol/gasoline blends, it is possible thatChaoHR,LinTC,ChaoMR,ChangFH,HuangCI,Chenmethanol/gasoline blends have lower effect on environ-C B, 2000. Effect of methanol-containing additive on theemission of carbonyl compounds from a heavy-duty dieselment than gasoline.engine. Journal of Hazxardous Materials, 73(1): 39 -54.da silva R, Cataluna R, Menezes E W de, Samios D, Piatnicki C3 ConclusionsM s, 2005. Effect of additives on the antiknock propertiesand reid vapor pressure of gasoline. 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