Catalyzed Gasoline Particulate Filters Reduce Secondary Organic Aerosol Production from Gasoline Direct Injection Vehicles

Abstract. Gasoline direct injection (GDI) vehicles have recently been identified as a significant source of carbonaceous aerosol, of both primary and secondary origin. Here we investigated primary emissions and secondary organic aerosol (SOA) from four GDI vehicles, two of which were also retrofitted with a prototype gasoline particulate filter (GPF). We studied two driving test cycles under cold- and hot-engine conditions. Emissions were characterized by proton transfer reaction time-of-flight mass spectrometry (gaseous non-methane organic compounds, NMOCs), aerosol mass spectrometry (sub-micron non-refractory particles) and light attenuation measurements (equivalent black carbon (eBC) determination using Aethalometers) together with supporting instrumentation. Atmospheric processing was simulated using the PSI mobile smog chamber (SC) and the potential aerosol mass oxidation flow reactor (OFR). Overall, primary and secondary particulate matter (PM) and NMOC emissions were dominated by the engine cold start, i.e., before thermal activation of the catalytic after-treatment system. Trends in the SOA oxygen to carbon ratio (O : C) for OFR and SC were related to different OH exposures, but divergences in the H : C remained unexplained. SOA yields agreed within experimental variability between the two systems, with a tendency for higher values in the OFR than in the SC (or, vice versa, lower values in the SC). A few aromatic compounds dominated the NMOC emissions, primarily benzene, toluene, xylene isomers/ethylbenzene and C3-benzene. A significant fraction of the SOA was explained by those compounds, based on comparison of effective SOA yield curves with those of toluene, o-xylene and 1,2,4-trimethylbenzene determined in our OFR, as well as others from literature. Remaining discrepancies, which were smaller in the SC and larger in the OFR, were up to a factor of 2 and may have resulted from diverse reasons including unaccounted precursors and matrix effects. GPF retrofitting significantly reduced primary PM through removal of refractory eBC and partially removed the minor POA fraction. At cold-started conditions it did not affect hydrocarbon emission factors, relative chemical composition of NMOCs or SOA formation, and likewise SOA yields and bulk composition remained unaffected. GPF-induced effects at hot-engine conditions deserve attention in further studies.

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Secondary Organic Aerosol Formation from On-road Gasoline Vehicles in China

10.5194/egusphere-egu2020-8093 ◽

2020 ◽

Author(s):

Hui Wang ◽

Rongzhi Tang ◽

Ruizhe Shen ◽

Ying Yu ◽

Kefan Liu ◽

...

Keyword(s):

Constant Velocity ◽

Secondary Organic Aerosol ◽

Direct Injection ◽

Fine Particulate Matter ◽

Organic Aerosol ◽

Gasoline Direct Injection ◽

Aerosol Formation ◽

Vehicle Exhaust ◽

Formation Potential ◽

Ethanol Content

Organic aerosol (OA) constitutes a significant fraction of the atmospheric fine particulate matter that influences both air quality and climate. Secondary organic aerosol (SOA), which is formed through photo-oxidation of organic vapors in the atmosphere, is a major component of OA. There are some studies indicating the major role of vehicles emissions in SOA formation in urban cities of China. However, SOA formation is complex and uncertain.Historically, the China fleet has been dominated by vehicles equipped with port-fuel injected (PFI), but the market share of vehicles equipped with gasoline direct injection engines (GDI) has increased dramatically. And 10% of renewable energy ethanol (E10) may be added to the gasoline of China market in the future. Go-PAM is one kind of potential aerosol mass for simulating SOA formation, which is designed and made by the University of Gothenburg.In this study, we focus on the influence of ethanol content (0% or 10%), engine types (GDI or PFI) and different engine loads (idling or constant velocity) to the SOA formation potential from gasoline motor cars emissions. We exposed the diluted emissions to a range of oxidation (O3 and OH) concentrations in the Go-PAM, resulting different OH exposures. We observed variations of different cases in SOA formation.Firstly, compared to PFI engine, GDI engine at idling loading has larger SOA mass concentrations. The peak SOA production of PFI engine at idling load occurred at equivalent photochemical age (EPA) of 3.8 days, which peak point occurred at larger EPA (4.8 days) for GDI engines. Secondly, there is no large difference between E10 and gasoline. Thirdly, OA enhancement is more obvious at idling (about 30-180 times) than at constant velocity (about 3-4 times) whatever engine is used. Generally, densities of particles at size of 70nm,140nm and 200nm keep growing from about 1.25 up to 1.45 g/cm3.The results of this study highlight the utility of Go-PAM for studying SOA formation potential from vehicle exhaust, and provide indications of the influence of ethanol content and different engines to SOA formation in China.

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Interactive comment on “Gas phase composition and secondary organic aerosol formation from gasoline direct injection vehicles investigated in a batch and flow reactor: effects of prototype gasoline particle filters.” By Simone M. Pieber et al

10.5194/acp-2017-942-rc1 ◽

2017 ◽

Author(s):

Anonymous

Keyword(s):

Phase Composition ◽

Gas Phase ◽

Particle Filters ◽

Flow Reactor ◽

Secondary Organic Aerosol ◽

Direct Injection ◽

Organic Aerosol ◽

Gasoline Direct Injection ◽

Aerosol Formation ◽

Secondary Organic Aerosol Formation

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Gas phase composition and secondary organic aerosol formation from gasoline direct injection vehicles investigated in batch and flow reactors: effects of prototype gasoline particle filters

10.5194/acp-2017-942 ◽

2017 ◽

Cited By ~ 2

Author(s):

Simone M. Pieber ◽

Nivedita K. Kumar ◽

Felix Klein ◽

Pierre Comte ◽

Deepika Bhattu ◽

...

Keyword(s):

Mass Spectrometry ◽

Particle Filters ◽

Secondary Organic Aerosol ◽

Direct Injection ◽

Organic Aerosol ◽

Gasoline Direct Injection ◽

Aerosol Formation ◽

Aerosol Mass ◽

Primary Emissions ◽

Engine Start

Abstract. Gasoline direct injection (GDI) vehicles have recently been identified as a significant source of carbonaceous aerosol, of both primary and secondary origin. Here we investigated primary emissions and secondary organic aerosol (SOA) formation from GDI vehicle exhaust for multiple vehicles and driving test cycles, and novel GDI after-treatment systems. Emissions were characterized by proton transfer reaction time-of-flight mass spectrometry (gaseous non-methane organic compounds, NMOCs), aerosol mass spectrometry (sub-micron non-refractory particles), and light attenuation measurements (equivalent black carbon (eBC) determination using Aethalometer measurements) together with supporting instrumentation. We evaluated the effect of retrofitted prototype gasoline particle filters (GPFs) on primary eBC, organic aerosol (OA), NMOCs, as well as SOA formation. Two regulatory driving test cycles were investigated, and the importance of distinct phases within these cycles (e.g. cold engine start, hot engine start, high speed driving) to primary emissions and secondary products was evaluated. Atmospheric processing was simulated using both the PSI mobile smog chamber (SC) and the potential aerosol mass oxidation flow reactor (OFR). GPF retrofitting was found to greatly decrease primary particulate matter (PM) through removal of eBC, but showed limited partial removal of the minor POA fraction, and had no detectable effect on either NMOC emissions (absolute emission factors or relative composition) or SOA production. In all tests, overall primary and secondary PM and NMOC emissions were dominated by the engine cold start, i.e. before thermal activation of the catalytic after-treatment system. Differences were found in the bulk compositional properties of SOA produced by the OFR and the SC (O : C and H : C ratios), while the SOA yields agree within our uncertainties, with a tendency for lower SOA yields in SC experiments. A few aromatic compounds are found to dominate the NMOC emissions (primarily benzene, toluene, xylene isomers and C3-benzenes). A large fraction (> 0.5) of the SOA production was explained by those compounds, based on investigation of reacted NMOC mass and comparison with SOA yield curves of toluene, o-xylene and 1,2,4-trimethylbenzene determined in our OFR within this study. Remaining differences in the obtained SOA yields may result from diverse reasons including aging conditions, unaccounted-for precursors and differences in SOA yields of aromatic hydrocarbons with different degrees of substitution, as well as experimental uncertainties in the assessment of particle and vapor wall losses.

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Comparisons of Laboratory and On-Road Type-Approval Cycles with Idling Emissions. Implications for Periodical Technical Inspection (PTI) Sensors

Sensors ◽

10.3390/s20205790 ◽

2020 ◽

Vol 20 (20) ◽

pp. 5790 ◽

Cited By ~ 1

Author(s):

Barouch Giechaskiel ◽

Tero Lähde ◽

Ricardo Suarez-Bertoa ◽

Victor Valverde ◽

Michael Clairotte

Keyword(s):

Direct Injection ◽

Spark Ignition ◽

Gasoline Direct Injection ◽

Compression Ignition ◽

Particulate Filters ◽

Technical Inspection ◽

Diesel Vehicles ◽

Type Approval ◽

Road Type ◽

Technical Specifications

For the type approval of compression ignition (diesel) and gasoline direct injection vehicles, a particle number (PN) limit of 6 × 1011 p/km is applicable. Diesel vehicles in circulation need to pass a periodical technical inspection (PTI) test, typically every two years, after the first four years of circulation. However, often the applicable smoke tests or on-board diagnostic (OBD) fault checks cannot identify malfunctions of the diesel particulate filters (DPFs). There are also serious concerns that a few high emitters are responsible for the majority of the emissions. For these reasons, a new PTI procedure at idle run with PN systems is under investigation. The correlations between type approval cycles and idle emissions are limited, especially for positive (spark) ignition vehicles. In this study the type approval PN emissions of 32 compression ignition and 56 spark ignition vehicles were compared to their idle PN concentrations from laboratory and on-road tests. The results confirmed that the idle test is applicable for diesel vehicles. The scatter for the spark ignition vehicles was much larger. Nevertheless, the proposed limit for diesel vehicles was also shown to be applicable for these vehicles. The technical specifications of the PTI sensors based on these findings were also discussed.

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Challenging Conditions for Gasoline Particulate Filters (GPFs)

Catalysts ◽

10.3390/catal12010070 ◽

2022 ◽

Vol 12 (1) ◽

pp. 70

Author(s):

Barouch Giechaskiel ◽

Anastasios Melas ◽

Victor Valverde ◽

Marcos Otura ◽

Giorgio Martini

Keyword(s):

Ambient Temperature ◽

Direct Injection ◽

Number System ◽

Gasoline Direct Injection ◽

Oxidation Catalyst ◽

Particulate Emissions ◽

High Concentration ◽

Rear Window ◽

Particulate Filters ◽

Low Efficiency

The emission limit of non-volatile particles (i.e., particles that do not evaporate at 350 °C) with size >23 nm, in combination with the real driving emissions (RDE) regulation in 2017, resulted in the introduction of gasoline particulate filters (GPFs) in all light-duty vehicles with gasoline direct injection engines in Europe. Even though there are studies that have examined the particulate emissions at or beyond the current RDE boundary conditions, there is a lack of studies combining most or all worst cases (i.e., conditions that increase the emissions). In this study, we challenged a fresh (i.e., no accumulation of soot or ash) “advanced” prototype GPF at different temperatures (down to −9 °C), aggressive drive cycles and hard accelerations (beyond the RDE limits), high payload (up to 90%), use of all auxiliaries (air conditioning, heating of the seats and the rear window), and cold starts independently or simultaneously. Under hot engine conditions, the increase of the particulate emissions due to higher payload and lower ambient temperature was 30–90%. The cold start at low ambient temperature, however, had an effect on the emissions of up to a factor of 20 for particles >23 nm or 300 when considering particles <23 nm. We proposed that the reason for these high emissions was the incomplete combustion and the low efficiency of the three-way oxidation catalyst. This resulted in a high concentration of species that were in the gaseous phase at the high temperature of the close-coupled GPF and thus could not be filtered by the GPF. As the exhaust gas cooled down, these precursor species formed particles that could not be evaporated at 350 °C (the temperature of the particle number system). These results highlight the importance of the proper calibration of the engine out emissions at all conditions, even when a GPF is installed.

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Morphology and size of the particles emitted from a gasoline-direct-injection-engine vehicle and their ageing in an environmental chamber

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-2781-2020 ◽

2020 ◽

Vol 20 (5) ◽

pp. 2781-2794 ◽

Cited By ~ 5

Author(s):

Jiaoping Xing ◽

Longyi Shao ◽

Wenbin Zhang ◽

Jianfei Peng ◽

Wenhua Wang ◽

...

Keyword(s):

Urban Environment ◽

Direct Injection ◽

Organic Aerosol ◽

Gasoline Direct Injection ◽

Soot Particles ◽

Pollution Levels ◽

Hot Start ◽

High Pollution ◽

Gdi Engine ◽

Organic Particles

Abstract. Air pollution is particularly severe in developing megacities, such as Beijing, where vehicles equipped with modern gasoline-direct-injection (GDI) engines are becoming one of major sources of the pollution. This study presents the characteristics of individual particles emitted by a GDI vehicle and their ageing in a smog chamber under the Beijing urban environment, as part of the Atmospheric Pollution & Human Health (APHH) research programme. Using transmission electron microscopy, we identified the particles emitted from a commercial GDI-engine vehicle running under various conditions, namely cold-start, hot-start, hot stabilized running, idle, and acceleration states. Our results showed that most of the particles were organic, soot, and Ca-rich ones, with small quantities of S-rich and metal-containing particles. In terms of particle size, the particles exhibited a bimodal distribution in number vs size, with one mode at 800–900 nm and the other at 140–240 nm. The numbers of organic particles emitted under hot-start and hot stabilized states were higher than those emitted under other conditions. The number of soot particles was higher under cold-start and acceleration states. Under the idle state, the proportion of Ca-rich particles was highest, although their absolute number was low. In addition to quantifying the types of particles emitted by the engine, we studied the ageing of the particles during 3.5 h of photochemical oxidation in an environmental chamber under the Beijing urban environment. Ageing transformed soot particles into core–shell structures, coated by secondary organic species, while the content of sulfur in Ca-rich and organic particles increased. Overall, the majority of particles from GDI-engine vehicles were organic and soot particles with submicron or nanometric size. The particles were highly reactive; they reacted in the atmosphere and changed their morphology and composition within hours via catalysed acidification that involved gaseous pollutants at high pollution levels in Beijing.Highlights. GDI-engine vehicles emitted a large amount of both primary and secondary organic aerosol (SOA). Higher numbers of organic particles were emitted under hot stabilized running and hot-start states. Sulfate and secondary organic aerosol formed on the surface of primary particles after ageing. Particles aged rapidly by catalysed acidification under high pollution levels in Beijing.

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