Size-resolved physico-chemical characterization of diesel exhaust particles and efficiency of exhaust aftertreatment

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@article{7148a1a3636e4bcc9bdcadfe5a9ed11d,
title = "Size-resolved physico-chemical characterization of diesel exhaust particles and efficiency of exhaust aftertreatment",
abstract = "Knowledge of physico-chemical characteristics of particle emissions from combustion engines is essential for various modelling purposes and environmental analysis. It is of particular interest to obtain emission factors of intermediate-volatility organic compounds (IVOC) and semi-volatile organic compounds (SVOC) which have not been comprehensively reported in the literature due to the limitations of characterisation methods. In the current study, a multi-stage Nano impactor and the two-dimensional gas chromatography (GC×GC) mass spectrometry (MS) technique were used to comprehensively characterise size fractionated particle phase emissions from a light-duty diesel engine based on the particle size, compound groups and carbon number. The number size distributions of particles between 1.2-1000 nm were also investigated. Exhaust gas samples were taken before a diesel oxidation catalyst (DOC), after the DOC and after the DOC combined with a catalysed diesel particulate filter (DPF). In samples taken before the DOC (engine-out), the total particulate IVOC+SVOC (I+SVOC) emission factor was approximately 105 milligrams per kilogram of fuel consumed (which was ~49% of the total particle mass) and the peak concentration of different classes of I+SVOC was found in the particle size bins close to 100 nm where most of the total particle mass was found. Alkanes, with maximum abundance at C24, were the most dominant class of I+SVOC in samples taken before and after the aftertreatment devices. Total particulate I+SVOC emissions were removed with ~75% efficiency using the DOC and by ~92% using the DOC+DPF. Alkanes, cycloalkanes, bicyclics and monoaromatics were all removed by >90% using the DOC+DPF; however, oxygenates were removed by only ~76% presumably due to the oxidation of different species within the aftertreatment system and reappearance as oxygenates. A high concentration of particles was measured in the sub-2.5 nm range. These particles were efficiently removed by the DOC+DPF due to both the loss of I+SVOC and physical filtration.",
keywords = "diesel engine, particulate matter, particle size magnifier, SVOC, DOC, DPF",
author = "{Zeraati Rezaei}, Soheil and Salim Alam and Hongming Xu and David Beddows and Roy Harrison",
year = "2019",
month = oct,
day = "3",
doi = "10.1016/j.atmosenv.2019.117021",
language = "English",
journal = "Atmospheric Environment",
issn = "1352-2310",
publisher = "Elsevier",

}

RIS

TY - JOUR

T1 - Size-resolved physico-chemical characterization of diesel exhaust particles and efficiency of exhaust aftertreatment

AU - Zeraati Rezaei, Soheil

AU - Alam, Salim

AU - Xu, Hongming

AU - Beddows, David

AU - Harrison, Roy

PY - 2019/10/3

Y1 - 2019/10/3

N2 - Knowledge of physico-chemical characteristics of particle emissions from combustion engines is essential for various modelling purposes and environmental analysis. It is of particular interest to obtain emission factors of intermediate-volatility organic compounds (IVOC) and semi-volatile organic compounds (SVOC) which have not been comprehensively reported in the literature due to the limitations of characterisation methods. In the current study, a multi-stage Nano impactor and the two-dimensional gas chromatography (GC×GC) mass spectrometry (MS) technique were used to comprehensively characterise size fractionated particle phase emissions from a light-duty diesel engine based on the particle size, compound groups and carbon number. The number size distributions of particles between 1.2-1000 nm were also investigated. Exhaust gas samples were taken before a diesel oxidation catalyst (DOC), after the DOC and after the DOC combined with a catalysed diesel particulate filter (DPF). In samples taken before the DOC (engine-out), the total particulate IVOC+SVOC (I+SVOC) emission factor was approximately 105 milligrams per kilogram of fuel consumed (which was ~49% of the total particle mass) and the peak concentration of different classes of I+SVOC was found in the particle size bins close to 100 nm where most of the total particle mass was found. Alkanes, with maximum abundance at C24, were the most dominant class of I+SVOC in samples taken before and after the aftertreatment devices. Total particulate I+SVOC emissions were removed with ~75% efficiency using the DOC and by ~92% using the DOC+DPF. Alkanes, cycloalkanes, bicyclics and monoaromatics were all removed by >90% using the DOC+DPF; however, oxygenates were removed by only ~76% presumably due to the oxidation of different species within the aftertreatment system and reappearance as oxygenates. A high concentration of particles was measured in the sub-2.5 nm range. These particles were efficiently removed by the DOC+DPF due to both the loss of I+SVOC and physical filtration.

AB - Knowledge of physico-chemical characteristics of particle emissions from combustion engines is essential for various modelling purposes and environmental analysis. It is of particular interest to obtain emission factors of intermediate-volatility organic compounds (IVOC) and semi-volatile organic compounds (SVOC) which have not been comprehensively reported in the literature due to the limitations of characterisation methods. In the current study, a multi-stage Nano impactor and the two-dimensional gas chromatography (GC×GC) mass spectrometry (MS) technique were used to comprehensively characterise size fractionated particle phase emissions from a light-duty diesel engine based on the particle size, compound groups and carbon number. The number size distributions of particles between 1.2-1000 nm were also investigated. Exhaust gas samples were taken before a diesel oxidation catalyst (DOC), after the DOC and after the DOC combined with a catalysed diesel particulate filter (DPF). In samples taken before the DOC (engine-out), the total particulate IVOC+SVOC (I+SVOC) emission factor was approximately 105 milligrams per kilogram of fuel consumed (which was ~49% of the total particle mass) and the peak concentration of different classes of I+SVOC was found in the particle size bins close to 100 nm where most of the total particle mass was found. Alkanes, with maximum abundance at C24, were the most dominant class of I+SVOC in samples taken before and after the aftertreatment devices. Total particulate I+SVOC emissions were removed with ~75% efficiency using the DOC and by ~92% using the DOC+DPF. Alkanes, cycloalkanes, bicyclics and monoaromatics were all removed by >90% using the DOC+DPF; however, oxygenates were removed by only ~76% presumably due to the oxidation of different species within the aftertreatment system and reappearance as oxygenates. A high concentration of particles was measured in the sub-2.5 nm range. These particles were efficiently removed by the DOC+DPF due to both the loss of I+SVOC and physical filtration.

KW - diesel engine

KW - particulate matter

KW - particle size magnifier

KW - SVOC

KW - DOC

KW - DPF

UR - http://www.scopus.com/inward/record.url?scp=85073010189&partnerID=8YFLogxK

U2 - 10.1016/j.atmosenv.2019.117021

DO - 10.1016/j.atmosenv.2019.117021

M3 - Article

JO - Atmospheric Environment

JF - Atmospheric Environment

SN - 1352-2310

M1 - 117021

ER -