Catalytic combustion of carbon particulate

Ciambelli, Paolo; Corbo, P.; Gambino, M.; Palma, Vincenzo; Vaccaro, Salvatore

doi:10.1016/0920-5861(95)00176-x

Cited by 67 publications

(30 citation statements)

References 9 publications

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“…As an example, Figure 9 shows results of a TAP experiment consisted of pulsing a very small amount of gas (~10 The activation energies of the uncatalyzed and ceria-catalyzed soot-O 2 reaction were determined by the Ozawa method [65][66][67] for several ceria catalysts (pure and Ladoped cerias calcined at 600, 800 and 1000 o C) and for 50% soot conversion, and the results obtained are included in Table 2. The activation energies both for the uncatalyzed and catalyzed reactions were in the range142-176 kJ/mol and values above 100 kJ/mole have been related to the dissociative chemisorption of O 2 on carbon sites [68] and, in the case of catalyzed reactions, to the interaction between catalyst and carbon surface [69]. These activation energy values also supported that the role of the ceria catalysts is to promote the transfer of oxygen from the gas phase to the carbon surface.…”

Section: Active Oxygen Mechanismmentioning

confidence: 63%

Diesel soot combustion ceria catalysts

Bueno‐López

2014

Applied Catalysis B: Environmental

395

243

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This review article summarizes the contents of the keynote lecture with the same tittle presented at the 7 th edition of the International Conference on Environmental Catalysis hold in Lyon (France) in September 2012. Different aspects of the ceria-catalyzed Diesel soot combustion reactions have been critically discussed, such as the high catalytic activity of ceria for Diesel soot combustion in comparison to some other potential catalysts, the potential ceria-catalyzed Diesel soot combustion mechanisms (the so-called NO 2 -assisted mechanism and the active oxygen mechanism) and the effect of ceria doping with suitable cations like those of Pr, La or Zr. Ceria must be doped in order to enhance thermal stability, but ceria doping also changes different physicochemical and catalytic properties of ceria. Zr-doping, for instance, has a double role on ceria as soot combustion catalyst: enhances ceria oxidation capacity of the adsorbed NOx species (positive effect) but stabilizes NO 2 on surface (negative effect). The surface properties of a ceria catalyst are usually more important than those of bulk: high surface area/small crystal size usually has a positive effect on the catalyst performance and, in mixed oxides, the surface composition also plays a role. The optimal dopant loading depends on the foreign cation being, for instance, around 5-10%, 20-30% and 50 mole % for La 3+ , Zr 4+ , and Pr 3+ / 4+ , respectively.Keywords: DPF regeneration; soot; ceria; doped-ceria; Diesel engine contamination. 2This review article summarizes the contents of the keynote lecture with the same tittle presented at the 7 th edition of the International Conference on Environmental Catalysis hold in Lyon (France) in September 2012. 1.-The problem.Soot particles are formed as undesired by-products in combustion process, being one of the main pollutants emitted by Diesel engines together with NOx, CO and unburned hydrocarbons [1]. Typical gas exhaust composition of a Diesel car, which is summarized in Table 1, is 30-80 ppm hydrocarbons, 200-1500 ppm CO, 300-1650 ppm NO (~ 0 ppm NO 2 ), 5-18% O 2 , > 2% H 2 O and > 2% CO 2 .Soot particles consist of a carbon nucleus with some inorganic material and adsorbed hydrocarbons, SO x , and water [2]. Figure 1 shows TEM images of a real soot sample. The single particles of few nanometers present an amorphous core surrounded by a graphitic shell, and such single particles agglomerate in larger entities with size typically in the range 0.1-10 µm [3].Several adverse effects on health have been attributed to soot. A fraction of these particles (the so-called PM-10, with size smaller than 10 m) can penetrate the respiratory tract and are deposited on lungs increasing cancer risk, asthma and bronchitis. The adsorbed hydrocarbons are mutagenic substances and SO x in contact with water form strong acid compounds.Diesel particle traps with different designs can be used for soot removal from gas streams, wall-flow monoliths being the most popular [3,4]. Figure 2 shows a commercial SiC Diesel Part...

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Section: Active Oxygen Mechanismmentioning

confidence: 63%

Diesel soot combustion ceria catalysts

Bueno‐López

2014

Applied Catalysis B: Environmental

395

243

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“…Temperature-programmed oxidation (TPO) and temperatureprogrammed desorption (TPD) have been proved to be expressive methods for this purpose (Ciambelli et al 1996;Neri et al 1997;Schmid et al 2011). Thereby, soot collected on filters is successively heated at oxidative (TPO) or inert atmosphere (TPD) and the emission products are quantified in dependence of applied temperature.…”

Section: Introductionmentioning

confidence: 99%

“…Schmid et al (2011) demonstrated the linear correlation of soot oxidation reactivity analyzed by TPO and soot structure determined by RM for various undoped soot types. Ciambelli et al (1996) examined the impact of a Cu/V/K-based catalyst on the thermo-chemical behavior of soot in a TPD experiment and could show that the total CO 2 emission is higher if soot is physically mixed with the catalyst than in the case of undoped soot.…”

Section: Introductionmentioning

confidence: 99%

Impact of Fe Content in Laboratory-Produced Soot Aerosol on its Composition, Structure, and Thermo-Chemical Properties

Bladt

Schmid

Kireeva

et al. 2012

Aerosol Science and Technology

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Soot aerosol, which is a major pollutant in the atmosphere of urban areas, often contains not only carbonaceous matter but also inorganic material. These species, for example, iron compounds, originated from impurities in fuel or lubricating oil, additives or engine wear may change the physico-chemical characteristics of soot and hence its environmental impact. We studied the change of composition, structure, and oxidation reactivity of laboratory-produced soot aerosol with varying iron content. Soot types of various iron contents were generated in a propane/air diffusion flame by adjusting the doping amount of iron pentacarbonyl Fe(CO) 5 to the flame. Scanning electron microscopy (SEM)/energy-dispersive Xray spectroscopy (EDX) was combined with cluster analysis (CA) to separate individual particles into definable groups of similar chemical composition representing the particle types in dependence of the iron content in soot. Raman microspectroscopy (RM) and infrared spectroscopy were applied for the characterization of the graphitic soot structure, hydrocarbons, and iron species. For the analysis of soot reactivity, temperature-programmed oxidation

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“…In the literature the published values of activation energy of thermal soot oxidation is found to cover a range between 140 and 210 kJ/mole. Low values of the order of 140-150 kJ/mole reported by Ciambelli et al [91] and Otto et al [92]. Neeft et al [93], report a somewhat lower value of 170 kJ/mol, for the oxidation of flame soot in a flow reactor with a different atmosphere (10% O2 in Ar).…”

Section: Resultsmentioning

confidence: 93%

“…This observation agrees with the results reported by Summers et al [97] and Lahaye et al [98] who found that the addition of Ce in the fuel is lowering the activation energy of soot oxidation from 170 to 120 kJ/mole. Ciambelli et al [99] also reported lower values of activation energy for soot oxidation after its impregnation with Cu/V/K catalyst. In contrast with the above observation Stanmore et al [94] reported unchanged activation energy of 210 kJ/mole (obtained for the uncatalyzed oxidation) for the soot oxidation with cerium present.…”

Section: Resultsmentioning

confidence: 95%

Experimental investigation of catalytic soot oxidation and pressure drop characteristics in wall-flow diesel particulate filters

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Catalytic combustion of carbon particulate

Cited by 67 publications

References 9 publications

Diesel soot combustion ceria catalysts

Diesel soot combustion ceria catalysts

Impact of Fe Content in Laboratory-Produced Soot Aerosol on its Composition, Structure, and Thermo-Chemical Properties

Experimental investigation of catalytic soot oxidation and pressure drop characteristics in wall-flow diesel particulate filters

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