Characterization of sulfated BaO-based NOx trap

Wei, Xinyi; Liu, Xinsheng; Deeba, Michel

doi:10.1016/j.apcatb.2004.04.021

Cited by 41 publications

(32 citation statements)

References 14 publications

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“…Efforts towards improving the catalytic tolerance against sulfur poisoning and designing highly active and stable novel catalysts are vital for the globalization of the NSR technology [14,15,[17][18][19][20]. Misono and Inui [21], Fritz and Pitchon [22] and several others [12,13,[23][24][25][26][27] reported detailed studies on the improvement and the durability enhancement of NSR catalysts.…”

Section: Introductionmentioning

confidence: 99%

SO uptake and release properties of TiO2/Al2O3 and BaO/TiO2/Al2O3 mixed oxide systems as NO storage materials

et al. 2012

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Section: Introductionmentioning

confidence: 99%

SO uptake and release properties of TiO2/Al2O3 and BaO/TiO2/Al2O3 mixed oxide systems as NO storage materials

et al. 2012

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“…[19][20][21][22][23] As a support material of the NSR catalysts, TiO 2 was found to have a noticeable ability to suppress sulfur deposition. 24 This was associated with the surface acidity of TiO 2 , inhibiting the adsorption of acidic sulfur species and making the sulfates less stable on the TiO 2 compared to other oxide supports.…”

Section: Introductionmentioning

confidence: 99%

Nature of the Ti−Ba Interactions on the BaO/TiO₂/Al₂O₃ NO_x Storage System

et al. 2009

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A ternary oxide-based NO x storage material in the form of BaO/TiO 2 /γ-Al 2 O 3 was synthesized and characterized. Thermally induced structural changes occurring on the surfaces of the TiO 2 /γ-Al 2 O 3 and BaO/ TiO 2 /γ-Al 2 O 3 systems were studied in a comparative manner within 300-1273 K via X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, and BET surface area analysis. The surface acidity of the studied oxide systems was also investigated via pyridine adsorption monitored by in-situ Fourier transform infrared (FTIR) spectroscopy. BaO/TiO 2 /γ-Al 2 O 3 ternary oxide was synthesized by incorporating different loadings of (8-20 wt %) BaO onto the TiO 2 /γ-Al 2 O 3 support material, which was originally prepared using the sol-gel method. In the TiO 2 /γ-Al 2 O 3 binary oxide support material, anatase phase exhibited a relatively high thermal stability at T e 1073 K. The presence of TiO 2 domains on the surface of the alumina particles was found to alter the surface acidity of alumina by providing new medium-strength Lewis acid sites. SEM/EDX results indicate that in the BaO/TiO 2 /γ-Al 2 O 3 system, TiO 2 domains present a significant affinity toward BaO and/or Ba(NO 3 ) 2 resulting in a strong Ti-Ba interaction and the formation of overlapping domains on the surface. The presence of TiO 2 also leads to a decrease in the decomposition temperature of the Ba(NO 3 ) 2 phase with respect to the Ti-free Ba(NO 3 ) 2 /γ-Al 2 O 3 system. Such a destabilization is likely to occur due to a weaker interaction between Ba(NO 3 ) 2 and γ-Al 2 O 3 domains in the ternary oxide as well as due to the change in the surface acidity in the presence of TiO 2 . At relatively high temperatures (e.g., 873-1273 K) formation of complex structures in the form of BaTiO 3 , Ba 1.23 Al 2.46 Ti 5.54 O 16 , BaTiO 5 , and/or Ba x Al y Ti z O n were also observed.

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“…[13][14][15] One of the areas that have been a major target in numerous studies [16][17][18][19] in the past decade is the development of an optimal support material that will improve the catalytic stability by assisting the formation of sulfur resistant species in the catalytic system. In several studies 14,15,[20][21][22][23][24][25][26] it was pointed out that titania addition to the conventional alumina support reduces the stability of the sulfates and the use of titania-containing mixed oxides as support materials provides a potential avenue for sulfur tolerance improvement. It was found out that the sulfates formed on TiO 2 are unstable, primarily due to the inherent acidity of this specific oxide surface.…”

Section: Introductionmentioning

confidence: 99%

Fine-Tuning the Dispersion and the Mobility of BaO Domains on NO_x Storage Materials via TiO₂ Anchoring Sites

2010

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In an attempt to control the surface dispersion and the mobility of BaO domains on NO x storage materials, TiO 2 /TiO x anchoring sites were introduced on/inside the conventional γ-Al 2 O 3 support matrix. BaO/TiO 2 / Al 2 O 3 ternary oxide materials were synthesized via two different sol-gel preparation techniques, with varying surface compositions and morphologies. The synthesized NO x storage materials were studied via XRD, Raman spectroscopy, BET surface area analysis, TPD, XPS, SEM, EDX-mapping, and in situ FTIR spectroscopy of adsorbed NO 2 . NO x uptake properties of the BaO/TiO 2 /Al 2 O 3 materials were found to be strongly influenced by the morphology and the surface structure of the TiO 2 /TiO x domains. An improved Ba surface dispersion was observed for the BaO/TiO 2 /Al 2 O 3 materials synthesized via the coprecipitation of alkoxide precursors, which was found to originate mostly from the increased fraction of accessible TiO 2 /TiO x sites on the surface. These TiO 2 /TiO x sites function as strong anchoring sites for surface BaO domains and can be tailored to enhance surface dispersion of BaO. TPD experiments suggested the presence of at least two different types of NO x species adsorbed on the TiO 2 /TiO x sites, with distinctively different thermal stabilities. The relative stability of the NO x species adsorbed on the BaO/TiO 2 /Al 2 O 3 system was found to increase in the following order: NO + /N 2 O 3 on alumina , nitrates on alumina < surface nitrates on BaO < bridged/bidentate nitrates on large/isolated TiO 2 clusters < bulk nitrates on BaO on alumina surface and bridged/bidentate nitrates on TiO 2 crystallites homogenously distributed on the surface < bulk nitrates on the BaO sites located on the TiO 2 domains.

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Characterization of sulfated BaO-based NOx trap

Cited by 41 publications

References 14 publications

SO uptake and release properties of TiO2/Al2O3 and BaO/TiO2/Al2O3 mixed oxide systems as NO storage materials

SO uptake and release properties of TiO2/Al2O3 and BaO/TiO2/Al2O3 mixed oxide systems as NO storage materials

Nature of the Ti−Ba Interactions on the BaO/TiO₂/Al₂O₃ NO_x Storage System

Fine-Tuning the Dispersion and the Mobility of BaO Domains on NO_x Storage Materials via TiO₂ Anchoring Sites

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Characterization of sulfated BaO-based NOx trap

Cited by 41 publications

References 14 publications

SO uptake and release properties of TiO2/Al2O3 and BaO/TiO2/Al2O3 mixed oxide systems as NO storage materials

SO uptake and release properties of TiO2/Al2O3 and BaO/TiO2/Al2O3 mixed oxide systems as NO storage materials

Nature of the Ti−Ba Interactions on the BaO/TiO2/Al2O3 NOx Storage System

Fine-Tuning the Dispersion and the Mobility of BaO Domains on NOx Storage Materials via TiO2 Anchoring Sites

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Nature of the Ti−Ba Interactions on the BaO/TiO₂/Al₂O₃ NO_x Storage System

Fine-Tuning the Dispersion and the Mobility of BaO Domains on NO_x Storage Materials via TiO₂ Anchoring Sites