Insight into the key aspects of the regeneration process in the NOx storage reduction (NSR) reaction probed using fast transient kinetics coupled with isotopically labelled 15NO over Pt and Rh-containing Ba/Al2O3 catalysts

Breen, John; Burch, Robbie; Fontaine, Céline; Hardacre, Christopher; Rioche, C.

doi:10.1016/j.apcatb.2007.12.016

Cited by 60 publications

(32 citation statements)

References 41 publications

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“…Breen et al 35 also observed two N 2 peaks in a single storage-reduction cycle. However, they did not observe the second peak in N 2 O during the storage since N 2 O is not formed at higher temperatures (3508C).…”

Section: Analysis and Discussionmentioning

confidence: 89%

“…The results in Figure 11 also confirm that the NH X species (NH 3 ) on the catalyst surface are oxidized predominantly by O 2 and to a lesser extent by NO (O 2 /NO 5 100 in the lean feed). Breen et al 35 attribute the formation of N 2 during the storage to NH 3 stored on the catalyst reacting with stored NOx, gas phase NOx or O 2 . However, our results do not agree with stored NOx playing a role in the formation of N 2 and N 2 O during the storage.…”

Section: Analysis and Discussionmentioning

confidence: 99%

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Performance features of Pt/BaO lean NOx trap with hydrogen as reductant

2009

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in Wiley InterScience (www.interscience.wiley.com).The performance of a model Pt/BaO/Al 2 O 3 monolith catalyst was studied using H 2 as the reductant. The dependence of product selectivities on operating parameters is reported, including the durations of regeneration and storage times, feed composition and temperature, and monolith temperature. The data are explained in terms of a phenomenological model factoring in the transport, kinetic, and spatio-temporal effects. The Pt/BaO catalyst exhibits high cycle-averaged NOx conversion above 1008C, generating a mixture of N 2 and byproducts NH 3 and N 2 O. The cycle-averaged NOx conversion exhibits a maximum at about 3008C corresponding to the NOx storage maximum. The N 2 selectivity exhibits a maximum at a somewhat higher temperature, at which point the NH 3 selectivity exhibits a minimum. This trend conveys the intermediate role of NH 3 in reacting with stored NOx. Both N 2 and N 2 O are also formed during the storage steps from the oxidation of NH x species produced during the regeneration.

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Section: Analysis and Discussionmentioning

confidence: 89%

Section: Analysis and Discussionmentioning

confidence: 99%

Performance features of Pt/BaO lean NOx trap with hydrogen as reductant

2009

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“…Figure 3 shows that the first peak of ammonia formation occurs 3 s after the introduction of the reducing CO/H 2 mixture. Such catalytic features have been previously reported [6,7,11]. Pihl et al [12] observed that the main ammonia formation detected in the outlet gas appears after several seconds, when the catalyst surface along the monolith channel is reduced and an excess of the reducing agents occurs at the monolith outlet.…”

Section: Resultsmentioning

confidence: 79%

“…Concerning the adsorption mechanism, it has been proved that the storage process is influenced by the NO oxidation in NO 2 and the transformation in different forms of NO x stored (nitrites and/or nitrates route). However, only a few of them are dedicated to the description of the chemical processes occurring under rich atmosphere with the subsequent reduction of ad-NO x species to nitrogen [2][3][4][5][6][7]. Concerning the reduction step, it has been demonstrated that hydrogen is the most efficient reducing agent due to its high reactivity particularly at low temperature [1,2].…”

Section: Introductionmentioning

confidence: 99%

Study of Ammonia Formation During the Purge of a Lean NO x Trap

et al. 2009

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The aim of this work was to study the formation of ammonia during the regeneration step of a commercial lean NO x Trap catalyst in real conditions. Experiments were carried out on an engine test bench equipped with 2.2 L common rail diesel engine. The aftertreatment system was composed of a commercial NSR monolith catalyst with a volume of 2.2 L. This material was composed of platinum, palladium and rhodium, as active components, with barium oxide and alumina as storage component and support, respectively. Catalytic measurements were carried out at 280°C. Particular attention has been paid to formation of ammonia during the purge using hydrogen and CO as reducing agents. The time dependency of the extent of ammonia formation and the influence of hydrogen concentration were carefully examined. It was observed that the temperature rose in the first step of the regeneration process, after the switch in rich conditions, due to the occurrence of exothermic oxidation (H 2 /O 2 , CO/O 2 ) accompanied with the releasing of available vacant noble metal sites which may provide a route for H 2 and NO dissociation and/or subsequent surface reactions leading to the ultimate formation of ammonia. It was found that ammonia formation strongly depends on the purge duration and on the concentration of the reducing agent available during the purge.

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“…In particular, catalysts Pt-Rh-La/Ba/washcoat exhibited 0.530 mmol(NO)/g at saturation at 300 C. Moreover, the Rh/Ba/Al 2 O 3 catalysts were reported to exhibit the highest NO x reduction activity among Pt-, Pd-and Rh-based catalysts (Breen et al, 2008;Abdulhamid et al, 2006). However, the total NO x conversion on the Rh/Ba/Al 2 O 3 catalysts was lower than that the other two metal-based NSR catalysts.…”

Section: Transition Metal -Doped Catalystsmentioning

confidence: 99%

A short review about NOx storage-reduction catalysts based on metal oxides and hydrotalcite-type anionic clays

Jabłońska¹,

Palomares

Węgrzyn³

et al. 2013

Acta Geodynamica Et Geomaterialia

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The increasing problem of atmospheric pollution by NO x has resulted in stricter regulations on their emissions. NO x storage/reduction (NSR) is considered as efficient catalytic technology to abate lean-burn NO x . A wide variety of catalysts have been extensively examined for this purpose. The use of metal oxides, hydrotalcites and their derivatives as NO x storage/reduction catalysts has been reviewed. Suitable combination particularly the catalytic redox component and the storage component can lead to improved activity in NO x decomposition and capturing under the lean-rich conditions. ARTICLE INFO

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Insight into the key aspects of the regeneration process in the NOx storage reduction (NSR) reaction probed using fast transient kinetics coupled with isotopically labelled 15NO over Pt and Rh-containing Ba/Al2O3 catalysts

Cited by 60 publications

References 41 publications

Performance features of Pt/BaO lean NOx trap with hydrogen as reductant

Performance features of Pt/BaO lean NOx trap with hydrogen as reductant

Study of Ammonia Formation During the Purge of a Lean NO x Trap

A short review about NOx storage-reduction catalysts based on metal oxides and hydrotalcite-type anionic clays

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