Impacts of methanol fuel on vehicular emissions: A review

Highlights

● Methanol effectively reduces CO, HC, CO₂, PM, and PN emissions of gasoline vehicles.

● Elemental composition of methanol directly affects the reduction of emissions.

● Several physicochemical properties of methanol help reduce vehicle emissions.

Abstract

The transport sector is a significant energy consumer and a major contributor to urban air pollution. At present, the substitution of cleaner fuel is one feasible way to deal with the growing energy demand and environmental pollution. Methanol has been recognized as a good alternative to gasoline due to its good combustion performance. In the past decades, many studies have investigated exhaust emissions using methanol-gasoline blends. However, the conclusions derived from different studies vary significantly, and the explanations for the effects of methanol blending on exhaust emissions are also inconsistent. This review summarizes the characteristics of CO, HC, NO_x, CO₂, and particulate emissions from methanol-gasoline blended fuels and pure methanol fuel. CO, HC, CO₂, particle mass (PM), and particle number (PN) emissions decrease when methanol-blended fuel is used in place of gasoline fuel. NO_x emission either decreases or increases depending on the test conditions, i.e., methanol content. Furthermore, this review synthesizes the mechanisms by which methanol-blended fuel influences pollutant emissions. This review provides insight into the pollutant emissions from methanol-blended fuel, which will aid policymakers in making energy strategy decisions that take urban air pollution, climate change, and energy security into account.

Graphical abstract

Keywords

Methanol fuel / Vehicular emission / Emission reduction / Cleaner fuel / Gasoline substitute

References

[1] Agarwal A K , Karare H , Dhar A . (2014). Combustion, performance, emissions and particulate characterization of a methanol–gasoline blend (gasohol) fuelled medium duty spark ignition transportation engine. Fuel Processing Technology, 121 : 16– 24

[2] Agarwal T , Singh A P , Agarwal A K . (2020). Development of port fuel injected methanol (M85)-fuelled two-wheeler for sustainable transport. Journal of Traffic and Transportation Engineering, 7( 3): 298– 311

[3] Ajav E A , Singh B , Bhattacharya T K . (1998). Performance of a stationary diesel engine using vapourized ethanol as supplementary fuel. Biomass and Bioenergy, 15( 6): 493– 502

[4] AQSIQ (2009a). Fuel methanol for motor vehicles, GB/T 23510-2009. Beijing, China: General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China (in Chinese)

[5] AQSIQ (2009b). Methanol Gasoline (M85) for motor vehicles, GB/T 23799-2009. Beijing, China: General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China (in Chinese)

[6] Awad O I , Mamat R , Ali O M , Sidik N A C , Yusaf T , Kadirgama K , Kettner M . (2018). Alcohol and ether as alternative fuels in spark ignition engine: A review. Renewable & Sustainable Energy Reviews, 82 : 2586– 2605

[7] Balki M K , Erdoğan S , Aydın S , Sayin C . (2020). The optimization of engine operating parameters via SWARA and ARAS hybrid method in a small SI engine using alternative fuels. Journal of Cleaner Production, 258 : 120685

[8] Balki M K , Sayin C . (2014). The effect of compression ratio on the performance, emissions and combustion of an SI (spark ignition) engine fueled with pure ethanol, methanol and unleaded gasoline. Energy, 71 : 194– 201

[9] Balki M K , Sayin C , Canakci M . (2014). The effect of different alcohol fuels on the performance, emission and combustion characteristics of a gasoline engine. Fuel, 115 : 901– 906

[10] Balki M K , Sayin C , Sarıkaya M . (2016). Optimization of the operating parameters based on Taguchi method in an SI engine used pure gasoline, ethanol and methanol. Fuel, 180 : 630– 637

[11] Bechtold R L, Goodman M B, Timbario T A (2007). Use of Methanol as a Transportation Fuel. Arlington: Methanol Institute

[12] Beddows D C S , Harrison R M . (2008). Comparison of average particle number emission factors for heavy and light duty vehicles derived from rolling chassis dynamometer and field studies. Atmospheric Environment, 42( 34): 7954– 7966

[13] BP (2020). BP Statistical Review of World Energy 2020. London: British Petroleum Company

[14] Bromberg L, Cheng W K (2010). Methanol as an alternative transportation fuel in the US: Options for sustainable and/or energy-secure transportation. Cambridge: Sloan Automotive Laboratory Massachusetts Institute of Technology

[15] Canakci M , Ozsezen A N , Alptekin E , Eyidogan M . (2013). Impact of alcohol–gasoline fuel blends on the exhaust emission of an SI engine. Renewable Energy, 52 : 111– 117

[16] Canakci M , Ozsezen A N , Turkcan A . (2009). Combustion analysis of preheated crude sunflower oil in an IDI diesel engine. Biomass and Bioenergy, 33( 5): 760– 767

[17] Çelik M B , Özdalyan B , Alkan F . (2011). The use of pure methanol as fuel at high compression ratio in a single cylinder gasoline engine. Fuel, 90( 4): 1591– 1598

[18] Cheng W K, Hamrin D, Heywood J B, Hochgreb S, Min K, Norris M (1993). An Overview of Hydrocarbon Emissions Mechanisms in Spark-Ignition Engines. SAE Technical Paper, No. 932708. Pennsylvania, USA: Society of Automotive Engineers

[19] Dai P , Ge Y , Lin Y , Su S , Liang B . (2013). Investigation on characteristics of exhaust and evaporative emissions from passenger cars fueled with gasoline/methanol blends. Fuel, 113 : 10– 16

[20] Durbin T D , Wilson R D , Norbeck J M , Miller J W , Huai T , Rhee S H . (2002). Estimates of the emission rates of ammonia from light-duty vehicles using standard chassis dynamometer test cycles. Atmospheric Environment, 36( 9): 1475– 1482

[21] Elfasakhany A (2015). Investigations on the effects of ethanol–methanol–gasoline blends in a spark-ignition engine: Performance and emissions analysis. Engineering Science and Technology, an International Journal, 18(4): 713−719

[22] Elfasakhany A . (2017). Investigations on performance and pollutant emissions of spark-ignition engines fueled with n-butanol–, isobutanol–, ethanol–, methanol–, and acetone–gasoline blends: A comparative study. Renewable & Sustainable Energy Reviews, 71 : 404– 413

[23] Farkade H S , Pathre A P . (2012). Experimental investigation of methanol, ethanol and butanol blends with gasoline on SI engine. International Journal of Emerging Technology and Advanced Engineering, 2( 4): 205– 215

[24] Gang L , Ying Y , Minghui Z , Xin Z , Liang J . (2019). Key technical contents of the China VI emission standards for diesel fuelled heavy-duty vehicles. Johnson Matthey Technology Review, 63( 1): 21– 31

[25] Geng P , Yao C . (2015). Experimental investigation on the combustion and particulate matter (PM) emissions from a port-fuel injection (PFI) gasoline engine fueled with methanol–ultralow sulfur gasoline blends. Fuel, 145 : 221– 227

[26] Ghadikolaei M A . (2016). Effect of alcohol blend and fumigation on regulated and unregulated emissions of IC engines:A review. Renewable & Sustainable Energy Reviews, 57 : 1440– 1495

[27] Göktaş M , Kemal Balki M , Sayin C , Canakci M . (2021). An evaluation of the use of alcohol fuels in SI engines in terms of performance, emission and combustion characteristics: A review. Fuel, 286 : 119425

[28] Gong H , Ge Y , Wang J , Yin H . (2017). Light-duty vehicle emissions control: A brief introduction to the China 6 emissions standard. Johnson Matthey Technology Review, 61( 4): 269– 278

[29] Hao Y , Deng S , Yang Y , Song W , Tong H , Qiu Z . (2019). Chemical composition of particulate matter from traffic emissions in a road tunnel in Xi’an, China. Aerosol and Air Quality Research, 19( 2): 234– 246

[30] Hove A, Qian W, Zhao K, Fuerst N K (2020). China Energy Transition Status Report 2020. Beijing: Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH

[31] Huai T , Durbin T D , Wayne Miller J , Norbeck J M . (2004). Estimates of the emission rates of nitrous oxide from light-duty vehicles using different chassis dynamometer test cycles. Atmospheric Environment, 38( 38): 6621– 6629

[32] IEA (2021). The Potential of Behavioural Interventions for Optimising Energy Use at Home. Paris: International Energy Agency (IEA)

[33] Kaiser E W, Siegl W O, Anderson R W (1994). Fuel Structure and the Nature of Engine-Out Emissions. SAE Technical Paper, No. 941960. Maryland: Society of Automotive Engineers

[34] Kaiser E W , Siegl W O , Henig Y I , Anderson R W , Trinker F H . (1991). Effect of fuel structure on emissions from a spark-ignited engine. Environmental Science & Technology, 25( 12): 2005– 2012

[35] Kak A, Kumar N, Singh B, Singh S, Gupta D (2015). Comparative Study of Emissions and Performance of Hydrogen Boosted SI Engine Powered by Gasoline Methanol Blend and Gasoline Ethanol Blend. SAE Technical Paper, No. 2015-01-1677. Detroit: SAE International

[36] Kalwar A , Singh A P , Agarwal A K . (2020). Utilization of primary alcohols in dual-fuel injection mode in a gasoline direct injection engine. Fuel, 276 : 118068

[37] Kleeman M J , Schauer J J , Cass G R . (2000). Size and composition distribution of fine particulate matter emitted from motor vehicles. Environmental Science & Technology, 34( 7): 1132– 1142

[38] Landälv I (2017). Methanol as a renewable fuel: A knowledge synthesis. 2015:08. Göteborg: The Swedish Knowledge Centre for Renewable Transportation Fuels (f3)

[39] Li L , Ge Y , Wang M , Li J , Peng Z , Song Y , Zhang L . (2015). Effect of gasoline/methanol blends on motorcycle emissions: Exhaust and evaporative emissions. Atmospheric Environment, 102 : 79– 85

[40] Li W Y , Li Z , Xie K C . (2009). The development of methanol industry and methanol fuel in China. Energy Sources. Part A, Recovery, Utilization, and Environmental Effects, 31( 18): 1673– 1679

[41] Li Y , Gong J , Deng Y , Yuan W , Fu J , Zhang B . (2017). Experimental comparative study on combustion, performance and emissions characteristics of methanol, ethanol and butanol in a spark ignition engine. Applied Thermal Engineering, 115 : 53– 63

[42] Liang B , Ge Y , Tan J , Han X , Gao L , Hao L , Ye W , Dai P . (2013). Comparison of PM emissions from a gasoline direct injected (GDI) vehicle and a port fuel injected (PFI) vehicle measured by electrical low pressure impactor (ELPI) with two fuels: Gasoline and M15 methanol gasoline. Journal of Aerosol Science, 57 : 22– 31

[43] Litzinger T , Stoner M , Hess H , Boehman A . (2000). Effects of oxygenated blending compounds on emissions from a turbocharged direct injection diesel engine. International Journal of Engine Research, 1( 1): 57– 70

[44] Liu H , Wang Z , Long Y , Xiang S , Wang J , Fatouraie M . (2015a). Comparative study on alcohol–gasoline and gasoline–alcohol Dual-Fuel Spark Ignition (DFSI) combustion for engine particle number (PN) reduction. Fuel, 159 : 250– 258

[45] Liu H , Wang Z , Long Y , Xiang S , Wang J , Wagnon S W . (2015b). Methanol-gasoline Dual-fuel Spark Ignition (DFSI) combustion with dual-injection for engine particle number (PN) reduction and fuel economy improvement. Energy, 89 : 1010– 1017

[46] Liu S , Clemente E R C , Hu T , Wei Y . (2007). Study of spark ignition engine fueled with methanol/gasoline fuel blends. Applied Thermal Engineering, 27( 11–12): 1904– 1910

[47] Liu X , Wang H , Zheng Z , Liu J , Reitz R D , Yao M . (2016). Development of a combined reduced primary reference fuel-alcohols (methanol/ethanol/propanols/butanols/n-pentanol) mechanism for engine applications. Energy, 114 : 542– 558

[48] Mallikarjun M V , Mamilla V R . (2009). Experimental study of exhaust emissions & performance analysis of multi cylinder S.I. engine when methanol used as an additive. International Journal of Electronic Engineering Research, 1( 3): 201– 212

[49] Mårald E . (2010). Methanol as future fuel: Efforts to develop alternative fuels in Sweden after the Oil Crisis. History and Technology, 26( 4): 335– 357

[50] Maricq M M . (2007). Chemical characterization of particulate emissions from diesel engines: A review. Journal of Aerosol Science, 38( 11): 1079– 1118

[51] Masum B M , Kalam M A , Masjuki H H , Palash S M , Fattah I M R . (2014). Performance and emission analysis of a multi cylinder gasoline engine operating at different alcohol–gasoline blends. RSC Advances, 4( 53): 27898– 27904

[52] Masum B M , Masjuki H H , Kalam M A , Fattah I M R , Palash S M , Abedin M J . (2013). Effect of ethanol–gasoline blend on NO_x emission in SI engine. Renewable & Sustainable Energy Reviews, 24 : 209– 222

[53] Maurya R K , Agarwal A K . (2014). Experimental investigations of performance, combustion and emission characteristics of ethanol and methanol fueled HCCI engine. Fuel Processing Technology, 126 : 30– 48

[54] MEE (2018). Limits and Measurement Methods for Emissions from Diesel Fuelled Heavy-Duty Vehicles (CHINA VI), GB 17691−2018. Beijing: Ministry of Ecology and Environment of the People’s Republic of China

[55] MEE (2020). China Mobile Source Environmental Management Annual Report. Beijing: Ministry of Ecology and Environment of the People’s Republic of China

[56] Melo T C C D , Machado G B , Belchior C R P , Colaço M J , Barros J E M , De Oliveira E J , De Oliveira D G . (2012). Hydrous ethanol–gasoline blends–combustion and emission investigations on a Flex-Fuel engine. Fuel, 97 : 796– 804

[57] Methanex (2020). 2019 Responsible Care and Sustainability Report. Vancouver: Methanex

[58] Mishra P C , Gupta A , Kumar A , Bose A . (2020). Methanol and petrol blended alternate fuel for future sustainable engine: A performance and emission analysis. Measurement, 155 : 107519

[59] Muñoz-Boado M M , Caldona E B . (2017). Gypsum-reinforced zeolite composite for particulate matter reduction from vehicular emissions. Journal of Environmental Chemical Engineering, 5( 3): 2631– 2638

[60] Nakata K, Utsumi S, Ota A, Kawatake K, Kawai T, Tsunooka T (2006). The Effect of Ethanol Fuel on a Spark Ignition Engine. SAE Technical Paper, No. 2006-01-3380. Toronto: Society of Automotive Engineers

[61] Nuthan Prasad B S , Pandey J K , Kumar G N . (2020). Impact of changing compression ratio on engine characteristics of an SI engine fueled with equi-volume blend of methanol and gasoline. Energy, 191 : 116605

[62] Ozsezen A N , Canakci M . (2011). Performance and combustion characteristics of alcohol–gasoline blends at wide-open throttle. Energy, 36( 5): 2747– 2752

[63] Ozsezen A N , Turkcan A , Sayin C , Canakci M . (2011). Comparison of performance and combustion parameters in a heavy-duty diesel engine fueled with iso-butanol/diesel fuel blends. Energy Exploration and Exploitation, 29( 5): 525– 541

[64] Pan D , Tao L , Sun K , Golston L M , Miller D J , Zhu T , Qin Y , Zhang Y , Mauzerall D L , Zondlo M A . (2020). Methane emissions from natural gas vehicles in China. Nature Communications, 11( 1): 1– 10

[65] Pant P , Harrison R M . (2013). Estimation of the contribution of road traffic emissions to particulate matter concentrations from field measurements: A review. Atmospheric Environment, 77 : 78– 97

[66] Pourkhesalian A M , Shamekhi A H , Salimi F . (2010). Alternative fuel and gasoline in an SI engine: A comparative study of performance and emissions characteristics. Fuel, 89( 5): 1056– 1063

[67] Qi D H , Liu S Q , Zhang C H , Bian Y Z . (2005). Properties, performance, and emissions of methanol-gasoline blends in a spark ignition engine. Proceedings of the Institution of Mechanical Engineers. Part D, Journal of Automobile Engineering, 219( 3): 405– 412

[68] Qian Y , Li Z , Yu L , Wang X , Lu X . (2019). Review of the state-of-the-art of particulate matter emissions from modern gasoline fueled engines. Applied Energy, 238 : 1269– 1298

[69] Rifal M, Sinaga N (2016). Impact of methanol-gasoline fuel blend on the fuel consumption and exhaust emission of a SI engine. In: AIP Conference Proceedings 1725, 020070 (2016). Semarang, Indonesia: American Institute of Physics, 1−7

[70] Sarathy S M , Farooq A , Kalghatgi G T . (2018). Recent progress in gasoline surrogate fuels. Progress in Energy and Combustion Science, 65 : 67– 108

[71] Sarathy S M , Oßwald P , Hansen N , Kohse-Höinghaus K . (2014). Alcohol combustion chemistry. Progress in Energy and Combustion Science, 44 : 40– 102

[72] Schröder J, Müller-Langer F, Aakko-Saksa P, Winther K, Baumgarten W, Lindgren M (2020). Methanol as Motor Fuel: Summary Report. Paris: International Energy Agency (IEA)

[73] Shen Y (2010). Methanol gasoline development in foreign countries and enlightenment to China. Sino-Global Energy, 15(12): 23−28 (in Chinese)

[74] Stanglmaier R H, Li J, Matthews R D (1999). The Effect of In-Cylinder Wall Wetting Location on the HC Emissions from SI Engines. SAE Technical Paper, No. 1999-01-0502. Michigan: Society of Automotive Engineers

[75] Su S , Ge Y , Wang X , Zhang M , Hao L , Tan J , Shi F , Guo D , Yang Z . (2020). Evaluating the in-service emissions of high-mileage dedicated methanol-fueled passenger cars: Regulated and unregulated emissions. Energies, 13( 11): 2680– 2694

[76] Sugita I W , Syaka D R B , Wahyudi A I . (2019). Effect of pertalite – methanol blends on performance and exhaust emission of a four-stroke 125 CC motorcycle engine. KnE Social Sciences, 3( 12): 384– 393

[77] Turner J W G , Lewis A G J , Akehurst S , Brace C J , Verhelst S , Vancoillie J , Sileghem L , Leach F , Edwards P P . (2018). Alcohol fuels for spark-ignition engines: Performance, efficiency and emission effects at mid to high blend rates for binary mixtures and pure components. Proceedings of the Institution of Mechanical Engineers. Part D, Journal of Automobile Engineering, 232 : 36– 56

[78] USEIA . (2021). Monthly Energy Review 2021. DOE/EIA-0035(2021/5): U.S. Energy Information Administration. Washington, DC : USEPA

[79] USEPA . (2010). Green Remediation Best Management Practices: Clean Fuel & Emission Technologies for Site Cleanup. EPA 542-F-10-008: U.S. Environmental Protection Agency. Washington, DC : USEPA

[80] Vancoillie J , Demuynck J , Sileghem L , Van De Ginste M , Verhelst S , Brabant L , Van Hoorebeke L . (2013). The potential of methanol as a fuel for flex-fuel and dedicated spark-ignition engines. Applied Energy, 102 : 140– 149

[81] Verhelst S , Turner J W G , Sileghem L , Vancoillie J . (2019). Methanol as a fuel for internal combustion engines. Progress in Energy and Combustion Science, 70 : 43– 88

[82] Vouitsis E , Ntziachristos L , Pistikopoulos P , Samaras Z , Chrysikou L , Samara C , Papadimitriou C , Samaras P , Sakellaropoulos G . (2009). An investigation on the physical, chemical and ecotoxicological characteristics of particulate matter emitted from light-duty vehicles. Environmental Pollution, 157( 8-9): 2320– 2327

[83] Wang X, Ge Y, Liu L, Gong H (2015a). Regulated, Carbonyl Emissions and Particulate Matter from a Dual-Fuel Passenger Car Burning Neat Methanol and Gasoline. SAE Technical Paper, No. 2015-01-1082. Detroit: SAE International

[84] Wang X , Ge Y , Liu L , Peng Z , Hao L , Yin H , Ding Y , Wang J . (2015b). Evaluation on toxic reduction and fuel economy of a gasoline direct injection- (GDI-) powered passenger car fueled with methanol–gasoline blends with various substitution ratios. Applied Energy, 157 : 134– 143

[85] Wang X , Ge Y , Zhang C , Tan J , Hao L , Liu J , Gong H . (2016). Effects of engine misfire on regulated, unregulated emissions from a methanol-fueled vehicle and its ozone forming potential. Applied Energy, 177 : 187– 195

[86] Wei Y , Liu S , Li H , Rui Y , Liu J , Wang Y . (2008). Effects of methanol/gasoline blends on a spark ignition engine performance and emissions. Energy & Fuels, 22( 2): 1254– 1259

[87] Wu C W , Chen R H , Pu J Y , Lin T H . (2004). The influence of air–fuel ratio on engine performance and pollutant emission of an SI engine using ethanol–gasoline-blended fuels. Atmospheric Environment, 38( 40): 7093– 7100

[88] Yusri I M , Mamat R , Najafi G , Razman A , Awad O I , Azmi W H , Ishak W F W , Shaiful A I M . (2017). Alcohol based automotive fuels from first four alcohol family in compression and spark ignition engine: A review on engine performance and exhaust emissions. Renewable & Sustainable Energy Reviews, 77 : 169– 181

[89] Zhang F, Shuai S, Wang J, Wang Z (2009). Influence of Methanol Gasoline Blend Fuel on Engine and Catalyst Performance. SAE Technical Paper, No. 2009-01-1182. Detroit: SAE International

[90] Zhang J, Nithyanandan K, Li Y, Lee C F, Huang Z (2015). Comparative Study of High-Alcohol-Content Gasoline Blends in an SI Engine. SAE Technical Paper, No. 2015-01-0891. Detroit: SAE International

[91] Zhao H , Ge Y , Hao C , Han X , Fu M , Yu L , Shah A N . (2010). Carbonyl compound emissions from passenger cars fueled with methanol/gasoline blends. Science of the Total Environment, 408( 17): 3607– 3613

[92] Zhao H , Ge Y , Tan J , Yin H , Guo J , Zhao W , Dai P . (2011). Effects of different mixing ratios on emissions from passenger cars fueled with methanol/gasoline blends. Journal of Environmental Sciences, 23( 11): 1831– 1838

[93] Zhao K (2019). A Brief Review of China’s Methanol Vehicle Pilot and Policy. Alexandria: Methanol Institute

[94] Zhao K, Dolan G, Chatterton C (2021). A Brief Review on Methanol-Fuelled Vehicles (MFV) in China and Implementation Policy. In: Agarwal A K, Valera H, Pexa M, Čedík J, eds. Methanol. Singapore: Springer, 139−159

[95] Zhen X , Wang Y . (2015). An overview of methanol as an internal combustion engine fuel. Renewable & Sustainable Energy Reviews, 52 : 477– 493

[96] Zhou N , Wu Q , Hu X . (2020). Research on the policy evolution of China’s new energy vehicles industry. Sustainability, 12( 9): 3629

Acknowledgements

This work was supported by the Tianjin Science and Technology Plan Project (China) (Nos. 18PTZWHZ00120, 19YFZCSF00960, 20YFZCSN01000, and 20JCYBJC01270) and The Fundamental Research Funds for the Central University of China (Nos. 63213074 and 63211075).

Abbreviations

Abbreviations	Nomenclature
ACEA	European Automobile Manufacturers’ Association
AFR	air/fuel ratio
Auto Alliance	Alliance of Automobile Manufacturers
BTE	brake thermal efficiency
CDTs	chassis dynamometer tests
CH4	methane
CO	carbon monoxide
CO2	carbon dioxide
C/H ratio	carbon/hydrogen ratio
DI	direct injection
EBTs	engine bench tests
EFs	emission factors
EGT	exhaust gas temperature
EMA	The Truck and Engine Manufacturers Association
EUDC	Extra-Urban Driving Cycle
FFV	flex-fuel vehicle
GDI	gasoline direct injection
HC	hydrocarbons
HCCI	homogeneous charge compression ignition
IEA	International Energy Agency
JAMA	Japan Automobile Manufacturers Association
MPFI	multipoint fuel injection
M3	consisting of 97% gasoline and 3% methanol by 　volume blends
M7	consisting of 93% gasoline and 7% methanol by 　volume blends
M10	consisting of 90% gasoline and 10% methanol by 　volume blends
M15	consisting of 85% gasoline and 10% methanol by 　volume blends
M20	consis ting of 80% gasoline and 20% methanol by 　volume blends
M30	consisting of 70% gasoline and 30% methanol by 　volume blends
M45	consisting of 55% gasoline and 45% methanol by 　volume blends
M50	consisting of 50% gasoline and 50% methanol by 　volume blends

M85	consisting of 15% gasoline and 85% methanol by 　volume blends
M100	pure methanol
NO	nitric oxide
NO2	nitrogen dioxide
NOx	nitrogen oxides
N2O	nitrous oxide
PAHs	polycyclic aromatic hydrocarbons
PFI	port-fuel injection
PM	particle mass
PN	particle number
SI	spark ignition
TWC	three-way catalytic converters
UDC	Urban Driving Cycle

RIGHTS & PERMISSIONS

2022 Higher Education Press