Evaluation of NOx Storage Catalysts for Lean Burn Gasoline Fueled Passenger Cars

Fekete, Nicholas P.; Kemmler, Roland; Voigtländer, D.; Krutzsch, B.; Zimmer, E.; Wenninger, G.; Strehlau, W.; Tillaart, J.A.A. van den; Leyrer, J.; Lox, E.S.; Müller, Werner

doi:10.4271/970746

Cited by 53 publications

(18 citation statements)

References 11 publications

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“…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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“…5,8 In a former study, thermodynamic calculations were performed on bulk materials in order to estimate the relative stabilities of carbonate and nitrate species on baria. 6,8 Using such an approach, Rodrigues et al 8 reported that at elevated temperatures, bulk BaCO 3 becomes more stable than bulk Ba(NO 3 ) 2 . Along these lines, it was argued that bulk Ba(NO 3 ) 2 could not be formed through the interaction of NO x (g) with bulk BaCO 3 under operational conditions.…”

Section: ■ Introductionmentioning

confidence: 99%

“…6,8 Using such an approach, Rodrigues et al 8 reported that at elevated temperatures, bulk BaCO 3 becomes more stable than bulk Ba(NO 3 ) 2 . Along these lines, it was argued that bulk Ba(NO 3 ) 2 could not be formed through the interaction of NO x (g) with bulk BaCO 3 under operational conditions. On the other hand, denisty functional theory (DFT) calculations associated with NO 2 and CO 2 adsorption on the BaO(100) 9 and BaCO 3 (110) 10 surfaces revealed that, although the adsorption strength of CO 2 is higher than that of NO 2 on BaO(100), 9 NO 2 adsorption on the BaCO 3 (110) surface should not be excluded.…”

Section: ■ Introductionmentioning

confidence: 99%

“…3,4 Under technical operating conditions, NSR processes are strongly influenced by the CO 2 and H 2 O species that are present in the exhaust stream. CO 2 and H 2 O may directly interact with the NO x storage material (i.e., BaO) and form BaCO 3 and Ba(OH) 2 species, respectively. 5,6 Furthermore, the presence of CO 2 in the exhaust stream during the lean cycle was found to decrease the NO x storage capacity (NSC) of NSR catalysts.…”

Section: ■ Introductionmentioning

confidence: 99%

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Interactive Surface Chemistry of CO₂ and NO₂ on Metal Oxide Surfaces: Competition for Catalytic Adsorption Sites and Reactivity

et al. 2013

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Interactive surface chemistry of CO 2 and NO 2 on BaO x /Pt(111) model catalyst surfaces were investigated via X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD) techniques with a particular emphasis on the competition between different adsorbates for the catalytic adsorption sites and adsorbateinduced morphological changes. After NO 2 adsorption, nitrated BaO x /Pt(111) surfaces do not reveal available adsorption sites for CO 2 at 323 K, irrespective of the presence/absence of exposed Pt sites on the surface. Although NO 2 adsorption on thick BaO x (>10MLE)/ Pt(111) overlayers at 323 K leads to the formation of predominantly nitrate species, NO 2 adsorption on the corresponding carbonated surface leads to the formation of coexisting nitrates and nitrites. The presence of carbonates on BaO x /Pt(111) overlayers does not prevent NO 2 uptake. Carbonated BaO x (1.5 MLE)/Pt(111) surfaces (with exposed Pt sites) obtained via CO 2 adsorption can also further interact with NO 2 , forming surface nitrate/nitrite species, accompanied by the transformation of surface carbonates into bulk carbonate species. These results suggest that the nitrate formation process requires the presence of two adjacent unoccupied adsorption sites. It is apparent that in the presence of both NO 2 and CO 2 , carbonate species formed on Lewis base (O 2− ) sites enable the formation of nitrites on Lewis acid (Ba 2+ ) sites. Thermal aging, nitration, and carbonation have a direct impact on the morphology of the two-/three-dimensional (2D/3D) BaO x aggregates on Pt(111). While thermal aging in vacuum leads to the sintering of the BaO x domains, nitration and carbonation results in redispersion and spreading of the BaO x domains on the Pt(111) substrate. ■ INTRODUCTIONMost of the heterogeneous catalytic reactions rely on the consecutive or simultaneous adsorption of reactants on the catalytically active sites for the generation of products. Along these lines, it is not uncommon for reactants, intermediates, and/or products bearing similar chemical structures to compete for similar catalytically active adsorption sites in heterogeneous catalytic processes. Thus, molecular level understanding of the competition phenomena occurring during the adsorption of reactants/intermediates/products on surfaces is a fundamentally crucial aspect for the elucidation of heterogeneous catalytic reaction mechanisms. Automotive exhaust emission catalysts are not an exception to this subject, where multiple catalytic pathways proceed in a parallel fashion in the presence of a large variety of reactants/intermediates/products. For instance, during the operation of the NO x storage-reduction (NSR) catalysts, 1,2 oxygen-rich exhaust gases of lean burn engines are treated in two different alternating operational cycles called lean (abundant in oxygen) and rich (abundant in hydrocarbon) cycles, where toxic NO x gases are initially oxidized/trapped in the solid state and then successively reduced to harmless N 2 .Despite considerable...

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“…The elimination of NO x produced by lean burn engines has been the subject of numerous developments [1][2][3][4][5]. NO x adsorber technology is an efficient solution to the NO x issue over quite a wide temperature range.…”

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confidence: 99%

Application of NOx Adsorber to Diesel Depollution: Performances and Durability

Dementhon

Colliou

Martin

et al. 2003

Oil & Gas Science and Technology - Rev. IFP

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Evaluation of NOx Storage Catalysts for Lean Burn Gasoline Fueled Passenger Cars

Cited by 53 publications

References 11 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

Interactive Surface Chemistry of CO₂ and NO₂ on Metal Oxide Surfaces: Competition for Catalytic Adsorption Sites and Reactivity

Application of NOx Adsorber to Diesel Depollution: Performances and Durability

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Evaluation of NOx Storage Catalysts for Lean Burn Gasoline Fueled Passenger Cars

Cited by 53 publications

References 11 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

Interactive Surface Chemistry of CO2 and NO2 on Metal Oxide Surfaces: Competition for Catalytic Adsorption Sites and Reactivity

Application of NOx Adsorber to Diesel Depollution: Performances and Durability

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Interactive Surface Chemistry of CO₂ and NO₂ on Metal Oxide Surfaces: Competition for Catalytic Adsorption Sites and Reactivity