Identifying critical factors in the regeneration of NOx-trap materials under realistic conditions using fast transient techniques

Breen, John; Rioche, C.; Burch, Robbie; Hardacre, Christopher; Meunier, Frédéric

doi:10.1016/j.apcatb.2006.11.002

Cited by 43 publications

(28 citation statements)

References 41 publications

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“…These results indicate that the introduced reductant at such operation mode (67 s lean/13 s rich) could regenerate the trapping sites more efficiently and a higher N 2 selectivity was obtained comparing to 67 s/6 s mode. Therefore, according to the experiments above, satisfied NO x conversion could be achieved by either a low concentration of reductant with a relatively long regeneration time or by a high concentration of reductant with a relatively short regeneration time, which is similar to results obtained by Breen et al [44].…”

Section: Dynamic No X Storage and Reduction Performancessupporting

confidence: 78%

“…It is worth noting, however, that supplying an excess reductant of H 2 may also increase the risk of NH 3 production due to a high H/N ratio, which ultimately reduces the selectivity to N 2 . Recent studies have found that NH 3 is an important intermediate at the reduction stage [44,45]. Although we detected a significant amount of NH 3 at low temperatures, its role needs further study and the emitted amount should be reasonably controlled when using H 2 as a reductant.…”

Section: Dynamic No X Storage and Reduction Performancesmentioning

confidence: 88%

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Effect of Co addition to Pt/Ba/Al2O3 system for NOx storage and reduction

Wang

2010

Applied Catalysis B: Environmental

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a b s t r a c tA comparative study of Pt/Ba/Al 2 O 3 , Co/Ba/Al 2 O 3 , Pt/Co/Al 2 O 3 and Pt/Co/Ba/Al 2 O 3 was performed in regards to their NO x storage capacities and NO oxidation abilities as a function of temperature. The nitrate stability and dynamic behaviors of NO x storage reduction during lean/rich fuel cycles using hydrogen as a reductant were also investigated over these catalysts. It was found that Pt/Co/Ba/Al 2 O 3 possessed the largest NO x storage capacity within the temperature range of 200-350 • C. The existence of Co not only improved the oxidation of NO to NO 2 under lean conditions, but also enhanced the release and reduction of NO x during the rich phase. The Pt and Co co-supported catalysts showed better NO x storage reduction activity and higher N 2 selectivity than Pt supported Ba/Al 2 O 3 catalysts within the tested temperature range. As for Pt/Co/Ba/Al 2 O 3 , high conversion was obtained at either a low reductant concentration with long duration time or a high reductant concentration with short duration time during the rich phase. In situ FTIR studies showed that NO x adsorption over Co-containing catalysts takes "nitrite route" as an important pathway. The intimate contact of Co and Ba/Al could accelerate nitrite/nitrate formation and the synergistic effect of Pt and Co could accelerate NO x reduction.

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Section: Dynamic No X Storage and Reduction Performancessupporting

confidence: 78%

Section: Dynamic No X Storage and Reduction Performancesmentioning

confidence: 88%

Effect of Co addition to Pt/Ba/Al2O3 system for NOx storage and reduction

Wang

2010

Applied Catalysis B: Environmental

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“…The 6 understanding of NSR technology has been hampered by the fact that various (usually non-7 realistic) reaction conditions were often used and a very large number of model materials with 8 varying formulations were investigated [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22]. 9 Several studies have been devoted to commercial NSR materials [23,24,25,26] and in 10 situ FTIR studies [27,28,29,30], but rarely the combination of the two has been reported. One 11 of the difficulties associated with commercial samples is the large number of components 12 present, making difficult the interpretation of in situ/operando IR spectra.…”

Section: Introductionmentioning

confidence: 99%

Effects of temperature and rich-phase composition on the performance of a commercial NOx-Storage-Reduction material

Dupré

Bazin

Marie

et al. 2016

Applied Catalysis B: Environmental

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“…[4,44] It should be noted, however, that NO 2 release at temperatures below the bulk decomposition temperature is known to occur both on single-crystal-based model systems [25] and on powder samples with realistic formulations. [45] To obtain more information on the nature of the nitrate species formed and released, we calculated difference spectra between the subsequent spectra taken within a single exposure/evacuation cycle (Figure 8). In these difference spectra, which reflect the spectral signature of the adsorbing/desorbing species only, there is a single broad absorption band located around 1410 cm…”

mentioning

confidence: 99%

Model NO_x Storage Materials at Realistic NO₂ Pressures

Desikusumastuti¹,

Schernich²,

Happel³

et al. 2009

ChemCatChem

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The interaction of NO2 with single‐crystal‐based model NOx storage materials, consisting of barium aluminate nanoparticles on Al2O3/NiAl(110), are investigated by time‐resolved infrared reflection absorption spectroscopy (TR‐IRAS) at realistic NO2 partial pressures up to 1.75 mbar. The data is compared to spectra obtained under ultrahigh vacuum (UHV) conditions on the same model system. At 300 K, the NO2 uptake at pressures around 1 mbar proceeds through rapid initial formation of surface nitrites and nitrates, similar to that under UHV conditions. The vibrational spectra of the surface species formed at realistic NO2 pressures are comparable to those for species formed under UHV conditions. Beyond the formation of surface species, the formation of bulk nitrates occurs, but is kinetically strongly hindered. At a very low rate, the formation of a disordered barium bulk nitrate is detected. At 500 K, this kinetic hindrance is overcome and the available Ba2+ is quantitatively converted to bulk Ba(NO3)2. The IRAS spectrum of these Ba(NO3)2 particles differs characteristically from those obtained for nitrate multilayers formed upon incomplete conversion under UHV conditions. In addition to the formation of bulk Ba(NO3)2, a more weakly bound disordered nitrate species is formed. This species gives rise to a dynamic NO2 uptake and release well below the decomposition temperature of bulk Ba(NO3)2. The experiments show that model studies under UHV conditions mainly provide information on the initial reaction mechanism, whereas the observation of actual bulk NOx storage phases requires experiments at realistic temperatures and pressures.

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Identifying critical factors in the regeneration of NOx-trap materials under realistic conditions using fast transient techniques

Cited by 43 publications

References 41 publications

Effect of Co addition to Pt/Ba/Al2O3 system for NOx storage and reduction

Effect of Co addition to Pt/Ba/Al2O3 system for NOx storage and reduction

Effects of temperature and rich-phase composition on the performance of a commercial NOx-Storage-Reduction material

Model NO_x Storage Materials at Realistic NO₂ Pressures

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Identifying critical factors in the regeneration of NOx-trap materials under realistic conditions using fast transient techniques

Cited by 43 publications

References 41 publications

Effect of Co addition to Pt/Ba/Al2O3 system for NOx storage and reduction

Effect of Co addition to Pt/Ba/Al2O3 system for NOx storage and reduction

Effects of temperature and rich-phase composition on the performance of a commercial NOx-Storage-Reduction material

Model NOx Storage Materials at Realistic NO2 Pressures

Contact Info

Product

Resources

About

Model NO_x Storage Materials at Realistic NO₂ Pressures