Fullerene-Like Soot from EuroIV Diesel Engine: Consequences for Catalytic Automotive Pollution Control

Müller, Jens-Oliver; Jentoft, Rolf E.; Rothe, Dieter; Jacob, Eberhard; Schlögl, Robert

doi:10.1023/b:toca.0000029756.50941.02

Cited by 94 publications

(76 citation statements)

References 4 publications

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“…The reactivity of diesel soot can vary widely with parameters such as the engine type [35], the fuel type [36,37], the engine load [38,39] and the presence of catalytically active ash species [40,41]. Numerous different types of soot are used in the oxidation studies in the literature, and the rate of catalytic soot oxidation scales with the inherent reactivity of the soot [23].…”

Section: Catalytic Soot Oxidationmentioning

confidence: 99%

Importance of the oxygen bond strength for catalytic activity in soot oxidation

Christensen

Grunwaldt

Jensen

2016

Applied Catalysis B: Environmental

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The oxygen bond strength on a catalyst, as measured by the heat of oxygen chemisorption, is observed to be a very important parameter for the activity of the catalyst in soot oxidation. With both intimate contact between soot and catalyst (tight contact) and with the solids stirred loosely together (loose contact) the rate constants for a number of catalytic materials outline a volcano curve when plotted against their heats of oxygen chemisorption. However, the optima of the volcanoes correspond to different heats of chemisorption for the two contact situations. In both cases the activation energies for soot oxidation follow linear Brønsted-Evans-Polanyi relationships with the heat of oxygen chemisorption. Among the tested metal or metal oxide catalysts Co 3 O 4 and CeO 2 were nearest to the optimal bond strength in tight contact oxidation, while Cr 2 O 3 was nearest to the optimum in loose contact oxidation. The optimum of the volcano curve in loose contact is estimated to occur between the bond strengths of α-Fe 2 O 3 and α-Cr 2 O 3 . Guided by an interpolation principle Fe a Cr b O x binary oxides were tested, and the activity of these oxides was observed to pass through an optimum for an FeCr 2 O x binary oxide catalyst, which exhibited a rate constant at 550 °C that was 2.3 times higher than the one for pure α-Cr 2 O 3 and 29 times higher than the one for pure α-Fe 2 O 3 .

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Section: Catalytic Soot Oxidationmentioning

confidence: 99%

Importance of the oxygen bond strength for catalytic activity in soot oxidation

Christensen

Grunwaldt

Jensen

2016

Applied Catalysis B: Environmental

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“…It is reasonable to raise the question of whether the improved combustion conditions alter the microstructure of soot particulates and thus also change the reactivity towards oxidation, a question that is of importance both for combustion optimisation and for the after-treatment of soot. In a preliminary study we found that the microstructure of soot emitted from a low emission Euro IV HD diesel engine was different from that of a Euro III HD engine running in black smoke mode, and that consequently the oxidation behaviour of the soot was different [6]. In this paper we present the results of a comparative study on microstructure and oxidative behaviour of the Euro IV HD soot, spark-discharge soot (GFG), and hexabenzocoronene (HBC) stressing the significance of the microstructure-controlled oxidative property of Euro IV HD diesel soot and the possible consequence for air pollution controls.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and oxidation behaviour of Euro IV diesel engine soot: a comparative study with synthetic model soot substances

et al. 2004

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In this study, the microstructure and oxidation behaviour of soot from the raw exhaust of a Euro IV test heavy duty (HD) diesel engine is investigated and compared to that of spark discharge soot and hexabenzocoronene (HBC, C 42 H 18 ). We find a microstructure-controlled reactivity toward oxidation of all three samples in 5% O 2 in N 2 . The spark discharge soot with its fine primary particles and fullerenoid structure has an onset temperature of 423 K for combustion, while the hexabenzocoronene with its well-ordered crystallites has a high onset temperature of 773 K. Due to an improved combustion process in the Euro IV HD diesel engine, the soot emitted consists of more fullerenoid-like or onion-like particles agglomerated in a chain-like secondary structure. The onset temperature of the Euro IV HD engine soot combustion is 573 K. Oxidation of the three samples produces only CO 2 and H 2 O. The different H 2 O production profiles can be assigned to the functionalised surface of the samples and depend on the soot structures and preparation route.

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“…The relatively low mass fraction of oxygen in soot carbon may be deceiving, since most of it is actually found on the surface in various functional groups, so that the soot particles do not behave as pure graphitic carbon in most atmospheric processes. The amount of oxygen at the surface of soot particles depends on combustion conditions, with more efficient combustion regimes resulting in higher abundance of oxygen and defective structures at the surface of the particles (Chughtai et al, 2002;Su et al, 2004). This in turn increases the chemical reactivity of the particles (including their thermochemical properties in soot analyzers) and their wettability in the atmosphere.…”

Section: Introductionmentioning

confidence: 99%

“…The shapes and intensities of Raman transitions are functions of the graphite crystal size, morphology and sample composition (Sze et al, 2001;Sadezky et al, 2005). High resolution transmission electron microscopy (HRTEM) revealed that the internal structure of combustion soot spherules depends strongly on the chemical and thermal environment under which they are formed and on the time available for annealing (Buseck et al, 1987;Su et al, 2004). Very rapidly formed soot particles are nearly amorphous, with only some signatures of short-range order (Pósfai et al, 1999;Grieco et al, 2000;Ferry et al, 2002;Wentzel et al, 2003), with fullerenic structures developing at slightly longer residence times in the combustion region.…”

Section: Introductionmentioning

confidence: 99%

Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols

Andreae

Gelencsér²

2006

Atmos. Chem. Phys.

1,768

1,033

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Abstract. Although the definition and measurement techniques for atmospheric "black carbon" ("BC") or "elemental carbon'' ("EC") have long been subjects of scientific controversy, the recent discovery of light-absorbing carbon that is not black ("brown carbon, Cbrown") makes it imperative to reassess and redefine the components that make up light-absorbing carbonaceous matter (LAC) in the atmosphere. Evidence for the atmospheric presence of Cbrown comes from (1) spectral aerosol light absorption measurements near specific combustion sources, (2) observations of spectral properties of water extracts of continental aerosol, (3) laboratory studies indicating the formation of light-absorbing organic matter in the atmosphere, and (4) indirectly from the chemical analogy of aerosol species to colored natural humic substances. We show that brown carbon may severely bias measurements of "BC" and "EC" over vast parts of the troposphere, especially those strongly polluted by biomass burning, where the mass concentration of Cbrown is high relative to that of soot carbon. Chemical measurements to determine "EC" are biased by the refractory nature of Cbrown as well as by complex matrix interferences. Optical measurements of "BC" suffer from a number of problems: (1) many of the presently used instruments introduce a substantial bias into the determination of aerosol light absorption, (2) there is no unique conversion factor between light absorption and "EC" or "BC" concentration in ambient aerosols, and (3) the difference in spectral properties between the different types of LAC, as well as the chemical complexity of Cbrown, lead to several conceptual as well as practical complications. We also suggest that due to the sharply increasing absorption of Cbrown towards the UV, single-wavelength light absorption measurements may not be adequate for the assessment of absorption of solar radiation in the troposphere. We discuss the possible consequences of these effects for our understanding of tropospheric processes, including their influence on UV-irradiance, atmospheric photochemistry and radiative transfer in clouds.

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Fullerene-Like Soot from EuroIV Diesel Engine: Consequences for Catalytic Automotive Pollution Control

Cited by 94 publications

References 4 publications

Importance of the oxygen bond strength for catalytic activity in soot oxidation

Importance of the oxygen bond strength for catalytic activity in soot oxidation

Microstructure and oxidation behaviour of Euro IV diesel engine soot: a comparative study with synthetic model soot substances

Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols

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