Sulphur dioxide interaction with NOx storage catalysts

Engström, Per; Amberntsson, Annika; Skoglundh, Magnus; Fridell, Erik; Smedler, Gudmund

doi:10.1016/s0926-3373(99)00060-0

Cited by 123 publications

(69 citation statements)

References 10 publications

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“…Deactivation of NSR catalysts is mainly caused by sulfur and thermal deterioration. Apart from the development of catalysts with higher tolerance of SO 2 or SO 2 -derived species [11,12], one of the major challenges is therefore the improvement of the thermal stability of NSR catalysts under operating conditions. Thermal deterioration occurs both due to the particle growth of the precious metals and due to the formation of mixed oxides such as aluminates, cerates, and zirconates by the reaction of NO x storage material with the support or compounds in the wash-coat [8,[13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Formation and stability of barium aluminate and cerate in NOx storage-reduction catalysts

Casapu

Grunwaldt

Maciejewski

et al. 2006

Applied Catalysis B: Environmental

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The formation and stability of BaAl 2 O 4 and BaCeO 3 in Pt-Ba/Al 2 O 3 and Pt-Ba/CeO 2 based NO x storage-reduction (NSR) catalyst has been investigated using kinetic measurements, X-ray diffraction, thermal analysis and X-ray absorption spectroscopy. In as-prepared state, the Ba-component in the NSR catalysts was made up of amorphous BaO and BaCO 3 . The formation of BaAl 2 O 4 started above 850°C, whereas the formation of BaCeO 3 was already observed at 800°C and was faster than that of BaAl 2 O 4 . The stability of BaAl 2 O 4 and BaCeO 3 in various liquid and gaseous atmospheres was different. BaAl 2 O 4 was rapidly hydrated at room temperature in the presence of water and transformed to Ba(NO 3 ) 2 and γ-alumina in the presence of HNO 3 , whereas BaCeO 3 was decomposed to much lower extent under these conditions. Interestingly, BaCeO 3 was transformed to Ba(NO 3 ) 2 /CeO 2 in the presence of NO 2 /H 2 O at 300 -500 °C. Also the presence of CO 2 led to decomposition of barium cerate, which has important consequences for the catalyst ageing under NO x -storage conditions and can be exploited for regeneration of thermally aged NSR-catalysts.

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Section: Introductionmentioning

confidence: 99%

Formation and stability of barium aluminate and cerate in NOx storage-reduction catalysts

Casapu

Grunwaldt

Maciejewski

et al. 2006

Applied Catalysis B: Environmental

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“…Chronologically, surface sulfates are the first to appear, followed by bulk BaSO 4 and bulk Al 2 (SO 4 ) 3 . Furthermore, the NO x storage capacity decrease is found to be proportional to the amount of SO 2 to which the BaO-based storage material has been exposed [9]. It is commonly accepted that SO 2 undergoes oxidation to SO 3 over precious metal sites.…”

Section: Introductionmentioning

confidence: 96%

“…SO 3 gradually accumulated on barium sites forms BaSO 4 , which prevents NO x storage to take place [9,11]. Thus, understanding the way sulfur poisoning occurs on BaO through interactions with SO 3 has aroused our interest in conducting a comprehensive multi-scale study on this matter.…”

Section: Introductionmentioning

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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“…The formation of nitrate on the storage compound is inhibited and thus the NO X storage ability deteriorates. Consequently, the deactivation of NSR catalysts depends on the amount of sulfur poisoning of the catalyst [12]. Sulfur deactivation also depends on the particle size of the sulfate produced by the NSR catalyst [13].…”

Section: Introductionmentioning

confidence: 99%

Improvement in sulfur desorption of NOX storage and reduction catalysts using a Ba–Ti composite oxide

Tanaka

Tajima

Kato

et al. 2011

Applied Catalysis B: Environmental

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A Ba-Ti composite oxide was formed on a NOx storage and reduction catalyst via impregnation of a Ba-Ti precursor solution composed of H 2 O 2 added to a complex prepared using the citric acid method. The structure of the Ba-Ti composite in solution was analyzed by chemical composition analysis and FT-Raman and UV-vis spectroscopy. MM2 calculations were performed to propose its chemical structure. Both Ba and Ti together were found to form a composite molecule in the solution.Furthermore, TEM-EDX and XRD analyses of the Ba-Ti composite oxide on the catalyst prepared by impregnation with the Ba-Ti composite aqueous solution revealed that Ba and Ti in the catalyst were highly dispersed at the nm scale. The formation of the Ba-Ti composite oxide on the NSR catalyst enhanced sulfur desorption efficiency and led to high-performance NO X conversion as a NO X storage and reduction activity catalyst after desulfation treatment. It was assumed that the existence of microscopic Ba compounds combined with Ti was efficient for the inhibition of the sintering of barium sulfate and its facile 2 decomposition. It was found that dispersion of Ba compounds for NO X storage materials using a Ba-Ti complex solution is an efficient way to improve the durability of NSR catalysts.

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Sulphur dioxide interaction with NOx storage catalysts

Cited by 123 publications

References 10 publications

Formation and stability of barium aluminate and cerate in NOx storage-reduction catalysts

Formation and stability of barium aluminate and cerate in NOx storage-reduction catalysts

Sulfur Deactivation of NO_xStorage Catalysts: A Multiscale Modeling Approach

Improvement in sulfur desorption of NOX storage and reduction catalysts using a Ba–Ti composite oxide

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Sulphur dioxide interaction with NOx storage catalysts

Cited by 123 publications

References 10 publications

Formation and stability of barium aluminate and cerate in NOx storage-reduction catalysts

Formation and stability of barium aluminate and cerate in NOx storage-reduction catalysts

Sulfur Deactivation of NOxStorage Catalysts: A Multiscale Modeling Approach

Improvement in sulfur desorption of NOX storage and reduction catalysts using a Ba–Ti composite oxide

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Sulfur Deactivation of NO_xStorage Catalysts: A Multiscale Modeling Approach