NO<sub>x</sub>Adsorption Study over Pt–Ba/Alumina Catalysts: FT-IR and Reactivity Study

Nova, Isabella; Castoldi, L.; Prinetto, F.; Santo, Vladimiro Dal; Lietti, Luca; Tronconi, Enrico; Forzatti, Pio; Ghiotti, G.; Psaro, Rinaldo; Recchia, Sandro

doi:10.1023/b:toca.0000029747.17327.2c

Cited by 67 publications

(66 citation statements)

References 16 publications

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“…Especially the fundamental mechanism of the initial storage process is currently under debate. Whereas several experimental studies point to sequential formation of nitrite and nitrate [9,[15][16][17][18] (cf. also [4]), theoretical calculations [19][20][21][22] and few recent experiUsing scanning tunneling microscopy (STM), molecular-beam (MB) methods and time-resolved infrared reflection absorption spectroscopy (TR-IRAS), we investigate the mechanism of initial NO x uptake on a model nitrogen storage and reduction (NSR) catalyst.…”

Section: Introductionmentioning

confidence: 99%

Interaction of NO₂ with Model NSR Catalysts: Metal–Oxide Interaction Controls Initial NO_x Storage Mechanism

et al. 2008

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Using scanning tunneling microscopy (STM), molecular-beam (MB) methods and time-resolved infrared reflection absorption spectroscopy (TR-IRAS), we investigate the mechanism of initial NO(x) uptake on a model nitrogen storage and reduction (NSR) catalyst. The model system is prepared by co-deposition of Pd metal particles and Ba-containing oxide particles onto an ordered alumina film on NiAl(110). We show that the metal-oxide interaction between the active noble metal particles and the NO(x) storage compound in NSR model catalysts plays an important role in the reaction mechanism. We suggest that strong interaction facilitates reverse spillover of activated oxygen species from the NO(x) storage compound to the metal. This process leads to partial oxidation of the metal nanoparticles and simultaneous stabilization of the surface nitrite intermediate.

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Section: Introductionmentioning

confidence: 99%

Interaction of NO₂ with Model NSR Catalysts: Metal–Oxide Interaction Controls Initial NO_x Storage Mechanism

et al. 2008

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“…[4,[7][8][9][10][11][12] A surfacescience-type model approach could provide the desired mechanistic and microkinetic information on the underlying processes. However, few attempts of modeling Ba-based NO x storage materials have been made to date.…”

Section: Introductionmentioning

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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“…Bands (1) and (2) are related to On the basis of the exposure and size dependent behavior it is concluded that the bands are surface-related with at least two different species contributing. Based on the literature, the straightforward assignment would be to monodentate nitrates [27][28][29][30][31][32]. An unambiguous assignment appears difficult, however, due to the complexity of NO related surface chemistry, showing a wealth of different surface species with partially overlapping bands (see e.g.…”

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Strong Size Effects in Supported Ionic Nanoparticles: Tailoring the Stability of NO x Storage Catalysts

et al. 2007

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Based on a well-defined model-catalyst approach, we study the particle size dependent properties of NO x storage materials. The single-crystal based model systems are prepared on an ordered Al 2 O 3 film, on which BaO nanoparticles are grown under ultrahigh-vacuum (UVH) conditions. Particle size and density are characterized by scanning tunneling microscopy (STM). The interaction with NO 2 is probed by molecular beam (MB) methods in combination with time-resolved IR reflection absorption spectroscopy (TR-IRAS). It is found that both, the stability and the formation kinetics of alumina supported barium nitrate nanoparticles show a strong dependence on particle size. Very small BaO particles are rapidly converted into nitrates, however, the resulting aggregates exhibit a strongly reduced thermal stability. Surface and bulk nitrate and nitrate features are identified by means of vibrational spectroscopy. It is concluded that the size dependencies are related to the formation and decomposition of surface-related BaNO x species the decomposition temperature of which can be tuned over an exceptionally large temperature interval. It is suggested that the stability of these surface NO x species is strongly modified by the underlying support.

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NO_xAdsorption Study over Pt–Ba/Alumina Catalysts: FT-IR and Reactivity Study

Cited by 67 publications

References 16 publications

Interaction of NO₂ with Model NSR Catalysts: Metal–Oxide Interaction Controls Initial NO_x Storage Mechanism

Interaction of NO₂ with Model NSR Catalysts: Metal–Oxide Interaction Controls Initial NO_x Storage Mechanism

Model NO_x Storage Materials at Realistic NO₂ Pressures

Strong Size Effects in Supported Ionic Nanoparticles: Tailoring the Stability of NO x Storage Catalysts

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NOxAdsorption Study over Pt–Ba/Alumina Catalysts: FT-IR and Reactivity Study

Cited by 67 publications

References 16 publications

Interaction of NO2 with Model NSR Catalysts: Metal–Oxide Interaction Controls Initial NOx Storage Mechanism

Interaction of NO2 with Model NSR Catalysts: Metal–Oxide Interaction Controls Initial NOx Storage Mechanism

Model NOx Storage Materials at Realistic NO2 Pressures

Strong Size Effects in Supported Ionic Nanoparticles: Tailoring the Stability of NO x Storage Catalysts

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NO_xAdsorption Study over Pt–Ba/Alumina Catalysts: FT-IR and Reactivity Study

Interaction of NO₂ with Model NSR Catalysts: Metal–Oxide Interaction Controls Initial NO_x Storage Mechanism

Interaction of NO₂ with Model NSR Catalysts: Metal–Oxide Interaction Controls Initial NO_x Storage Mechanism

Model NO_x Storage Materials at Realistic NO₂ Pressures