A mechanistic simulation model for<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si58.gif" display="inline" overflow="scroll"><mml:msub><mml:mrow><mml:mi>NO</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:math>storage catalyst dynamics

Tuttlies, Ute; Schmeißer, Volker; Eigenberger, Gerhart

doi:10.1016/j.ces.2004.08.026

Cited by 61 publications

(29 citation statements)

References 8 publications

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“…Simultaneously, the particle surface at the nitrate front decreases. As shape and size distribution of the nanoparticles are unknown, equation (6) for the specific surface area a p has been introduced to empirically account for this effect.…”

Section: Modellingmentioning

confidence: 99%

“…Following the reduced model developed in [5,6], a nitrate shell around each storage particle is formed during storage ( figure 1). NO, NO 2 and O 2 have to diffuse through this growing shell to react to nitrate according to equation (st1, st2) of table 3.…”

Section: Modellingmentioning

confidence: 99%

“…A detailed, two-dimensional mechanistic simulation model for NO x -storage catalyst dynamics had been developed previously, describing the strongly different dynamics of the storage and regeneration process [5,6]. Due to the higher molar volume of barium nitrate, the storage process is governed by slow diffusion of the gaseous reactants through a dense nitrate shell, growing progressively from the surface into the bulk of the barium clusters (see figure 1).…”

Section: Introductionmentioning

confidence: 99%

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Towards a realistic simulation model for NOx-storage catalyst dynamics

2007

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A model of a Pt/Rh/Ce/Ba/Al 2 O 3 -NO x -storage catalyst has been developed. It considers the influence of typical exhaust components on the NO-oxidation and NO x -reduction reactions under realistic flow conditions over a wide temperature range. The NO x -storage dynamics are limited by the diffusion of the reactants into the Ba-particle through an increasingly thick, dense nitrate layer. The regeneration reaction instead is fast since the nitrate shell breaks up. By calculation of the nitrate front position and the nitrate fraction in the Ba-particle, it is possible to describe the complex dynamic behaviour of the NSC.List of symbols a geo geometric washcoat surface (m 2 /m 3 ) a p particle surface (m 2 /m 3 ) a p max maximum particle surface (m 2 /m 3 ) a p min minimum particle surface (m 2 /m 3 ) c p Ba-densitiy of the storage particle (mol/m 3 ) c gas molar density of the gas (mol/m 3 ) D b diffusion coefficient in the gas bulk (m 2 /s) D p st diffusion coefficient in the particle (st.) (m 2 /s) D p reg diffusion coefficient in the particle (reg.) (m 2 /s) E a activation energy (J/mol) I i inhibition term of reaction i (-) k i frequency factor of reaction i (mol/m 3 s) r i reaction rate of reaction i (mol/m 3 s) R molar gas constant (8.314) (J/molAE K) R p storage particle radius (m) t time (s)

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Section: Modellingmentioning

confidence: 99%

Section: Modellingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Towards a realistic simulation model for NOx-storage catalyst dynamics

2007

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“…At low Ba-loading the NO x storage efficiency curve grows parallel with the increase of the concentration of LT-BaCO 3 , indicating that this phase contributes mainly to the storage activity. At higher Ba-loading, once the HT-BaCO 3 phase starts to form, the NO x storage efficiency decreases, indicating that HT-BaCO 3 shows a poor NO x storage activity, comparable to that of bulk BaCO 3 (not shown) and is affected by diffusional limitation [28][29][30].…”

Section: Influence Of Ba-loading On Thermal Stability and No X Storagmentioning

confidence: 99%

Role and distribution of different Ba-containing phases in supported Pt–Ba NSR catalysts

2007

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NO x storage-reduction catalysts with Ba-loading varying from 0 wt.% to 28 wt.% were investigated concerning stability of Ba phases and NO x storage-reduction efficiency. For Pt-Ba/Al 2 O 3 three different Ba-containing phases with different thermal stability are distinguished based on their interaction with the support. The relative concentration of these phases varies with the Ba-loading and NO x storage tests indicated that the BaCO 3 phase decomposing between 400°C and 800°C (LT-BaCO 3 ) is the most efficient Ba containing phase for NO x storage. Similar investigations of Pt-Ba catalysts supported on CeO 2 , SiO 2 and ZrO 2 showed that the relative amount of LT-BaCO 3 phase depends also on the support material. NO x storage measurements confirmed a correlation between the concentration of LT-BaCO 3 and NO x storage efficiency. Basicity and textural properties of the support are identified as crucial parameters for efficient NO x storage catalysts.

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“…Note that the impact of internal transport was not taken into account in this study. In order to describe more accurately the LNT operation, the impact of internal porosity variation on the effective species diffusivity would have to be accounted for [39]. Pressure is calculated from the energy balance inside the reactor volume [35] …”

Section: Reactor Modelmentioning

confidence: 99%

Sulfur Deactivation of NO_xStorage Catalysts: A Multiscale Modeling Approach

Rankovic

Chizallet

Nicolle

et al. 2013

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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Re´sume´-Empoisonnement des mate´riaux de stockage des NO x par le soufre : approche multi-e´chelles -Les pie`ges a`NO x repre´sentent une technologie prometteuse pour la re´duction des e´missions d'oxydes d'azote issus des moteurs ope´rant en me´lange pauvre. Leur utilisation est limite´e par la pre´sence de compose´s soufre´s dans les gaz d'e´chappement. Le soufre contenu dans le carburant et le lubrifiant est oxyde´lors de la combustion en SO 2 et SO 3 . Ces oxydes de soufre pre´sentent une forte affinite´pour le mate´riau de stockage du pie`ge, la formation de sulfate e´tant favorise´e thermodynamiquement. Cette formation contribue au blocage des sites d'adsorption des NO x et influence l'ope´ration de l'organe de post-traitement. La mode´lisation mole´culaire repre´sente un outil pre´cieux pour pre´dire le comportement et les performances du syste`me catalytique. Notre e´tude pre´sente une me´thodologie d'exploitation des calculs ab initio pour la formulation de mode`les cine´tiques de´veloppe´s dans la librairie de post-traitement ve´hicule IFP Exhaust. Nous illustrons notre approche par le cas de l'adsorption de SO 3 sur un mate´riau mode`le, BaO. Afin d'obtenir une description fide`le du mate´riau de stockage re´el, l'adsorption de SO 3 est de´crite sur plusieurs sites : terrasses, marches, crans et le site massique. Des analyses de sensibilite´et de vitesses de re´actions permettent d'obtenir une compre´hension plus approfondie des phe´nome`nes d'empoisonnement mis en jeu.Abstract -Sulfur Deactivation of NO x Storage Catalysts: A Multiscale Modeling ApproachLean NO x Trap (LNT) catalysts, a promising solution for reducing the noxious nitrogen oxide emissions from the lean burn and Diesel engines, are technologically limited by the presence of sulfur in the exhaust gas stream. Sulfur stemming from both fuels and lubricating oils is oxidized during the combustion event and mainly exists as SO x (SO 2 and SO 3 ) in the exhaust. Sulfur oxides interact strongly with the NO x trapping material of a LNT to form thermodynamically favored sulfate species, consequently leading to the blockage of NO x sorption sites and altering the catalyst operation. Molecular and kinetic modeling represent a valuable tool for predicting system behavior and evaluating catalytic performances. The present paper demonstrates how fundamental ab initio calculations can be used as a valuable source for designing kinetic models developed in the IFP Exhaust library, intended for vehicle simulations. The concrete example we chose to illustrate our

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A mechanistic simulation model forNOxstorage catalyst dynamics

Cited by 61 publications

References 8 publications

Towards a realistic simulation model for NOx-storage catalyst dynamics

Towards a realistic simulation model for NOx-storage catalyst dynamics

Role and distribution of different Ba-containing phases in supported Pt–Ba NSR catalysts

Sulfur Deactivation of NO_xStorage Catalysts: A Multiscale Modeling Approach

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A mechanistic simulation model forNOxstorage catalyst dynamics

Cited by 61 publications

References 8 publications

Towards a realistic simulation model for NOx-storage catalyst dynamics

Towards a realistic simulation model for NOx-storage catalyst dynamics

Role and distribution of different Ba-containing phases in supported Pt–Ba NSR catalysts

Sulfur Deactivation of NOxStorage Catalysts: A Multiscale Modeling Approach

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Sulfur Deactivation of NO_xStorage Catalysts: A Multiscale Modeling Approach