Comparative study of structural properties and NOx storage-reduction behavior of Pt/Ba/CeO2 and Pt/Ba/Al2O3

Casapu, Maria; Grunwaldt, Jan‐Dierk; Maciejewski, Marek; Krumeich, Frank; Baiker, Alfons; Wittrock, M.; Eckhoff, S.

doi:10.1016/j.apcatb.2007.09.030

Cited by 38 publications

(41 citation statements)

References 47 publications

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“…It has been reported that Pt is more likely to be in its oxidative state on ceria due to the high oxygen storage ability of ceria [20], while metallic Pt is supposed to be the active site for NO oxidation and reduction. Therefore, a H 2 reduction pretreatment is proposed to reactivate Pt sites before the NSR experiment [20].…”

Section: Cyclic No X Storage Reduction Testsmentioning

confidence: 99%

“…This catalyst is supposed to reduce NO x emission under a cyclic lean/rich mode for diesel or lean-burn gasoline engines. In a typical lean engine operation, NO is oxidized to NO 2 over noble metals and then stored as nitrites and/or nitrates on the storage components Pt particles during the lean phase [20]. To avoid such influence, a pre-reduction treatment at mild conditions was suggested to reactivate Pt on Pt/Ba/CeO 2 , leading to significant enhancement in NSR performance.…”

Section: Introductionmentioning

confidence: 99%

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Effects of temperature and reductant type on the process of NOx storage reduction over Pt/Ba/CeO2 catalysts

Wang

2011

Applied Catalysis B: Environmental

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a b s t r a c tThe influences of temperature and reductant type on NO x storage and reduction behavior were studied by transient lean/rich cycles and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments over Pt/Ba/CeO 2 catalysts. It is found that the reducing ability of H 2 is more predominant than that of CO and C 3 H 6 especially at low temperatures. DRIFTS results showed that NO x can be stored as nitrates on both Ba and Ce sites by replacing carbonates species during the lean phase. During the rich phase, however, H 2 regenerated Ba storage sites more effectively than did CO and C 3 H 6 , and Ba(NO 3 ) 2 could be easier reduced than Ce(NO 3 ) 4 . The relatively low reduction performance of CO was attributed to Pt sites being poisoned by CO, which affected low temperature performance, and by carbonates formation, which affected high temperature conversions. The least reactivity of C 3 H 6 was due to its lowest activation ability by the catalysts. Furthermore, water addition had a positive effect on CO reduction ability at 200• C but little influence at elevated temperatures. It was assumed that H 2 O improved the low temperature NO x reduction process by alleviating CO poisoning of Pt.

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Section: Cyclic No X Storage Reduction Testsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of temperature and reductant type on the process of NOx storage reduction over Pt/Ba/CeO2 catalysts

Wang

2011

Applied Catalysis B: Environmental

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“…NO x uptake of the SO 2 -treated ceria-based catalysts was reduced to 43 %, while for the aluminabased catalyst NO x uptake decreased to 23 %. However, it was indicated that Pt (0.74 wt.%)/Ba (15.5 wt.%)/CeO 2 exhibited inferior NO x storage performance, particularly the reduction/regeneration activity compared to the Al 2 O 3 supported catalysts (Casapu et al, 2008). Authors proposed that the incomplete reduction of stored NO x species by Pt/Ba/CeO 2 was caused by faster and more profound re-oxidation of Pt particles during the lean period.…”

Section: Other Metal Oxide Supportsmentioning

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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“…2 In the case of motor vehicles the elimination of these species is usually carried out through its reduction to N 2 using the conventional three-way catalysts which presents Pt, Pd, and Rh in its active phase, [3][4][5] being here a central reaction the NO reduction with CO (NO + CO → 1 2 N 2 + CO 2 ) since these gases are among the main contaminants emitted by the motor vehicles. Furthermore, other catalysts based on noble metals dispersed on a support were also tested for the NO x elimination 6,7 as those based on Ru, 8 Rh, 9 Ir, [10][11][12] Pd, [13][14][15] Pt, [16][17][18][19][20][21][22] Au, [23][24][25][26] Ag, [27][28][29][30] and also on alloys of these metals with cheaper metals. 8,9,20,22,31,32 In some cases the noble metal was successfully replaced by other elements.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, other catalysts based on noble metals dispersed on a support were also tested for the NO x elimination 6,7 as those based on Ru, 8 Rh, 9 Ir, [10][11][12] Pd, [13][14][15] Pt, [16][17][18][19][20][21][22] Au, [23][24][25][26] Ag, [27][28][29][30] and also on alloys of these metals with cheaper metals. 8,9,20,22,31,32 In some cases the noble metal was successfully replaced by other elements. [33][34][35][36][37] Two general methods are used for the elimination of the NO x species from the exhaust gas emissions employing solid catalysts, (i) the Selective Catalytic Reduction (SCR) 38 and (ii) the NO x Storage-Reduction (NSR), 39,40 respectively, used for stationary and for non-stationary NO x sources.…”

Section: Introductionmentioning

confidence: 99%

A DFT study of the NO dissociation on gold surfaces doped with transition metals

Fajín

Cordeiro

Gomes

2013

The Journal of Chemical Physics

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The NO dissociation on a series of doped gold surfaces (type TM n @Au(111) or TM n @Au(110), with TM n = Ni, Ir, Rh, or Ag and referring n to the number of dopant atoms per unit cell) was investigated through periodic density functional theory calculations. Generally, doping of Au (111) and Au(110) matrices was found to strengthen the interaction with NO species, with the exception of Ag, and was found to increase the energy barrier for dissociation, with the exception of Ni on Au(111). The calculations suggest that the NO dissociation is only possible in the case of the Ir@Au(110) bimetallic surface but only at high temperatures. The increase of the contents of Ir on Au(110) was found to improve significantly the catalytic activity of gold towards the NO dissociation (E act = ∼1 eV). Nevertheless, this energy barrier is almost the double of that calculated for NO dissociation on pure Ir(110). However, mixing the two most interesting dopant atoms resulted in a catalyst model of the type Ir@Ni(110) that was found to decrease the energy barrier to values close to those calculated for pure Ir surfaces, i.e., ∼0.4 eV, and at the same time the dissociation reaction became mildly exothermic.

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Comparative study of structural properties and NOx storage-reduction behavior of Pt/Ba/CeO2 and Pt/Ba/Al2O3

Cited by 38 publications

References 47 publications

Effects of temperature and reductant type on the process of NOx storage reduction over Pt/Ba/CeO2 catalysts

Effects of temperature and reductant type on the process of NOx storage reduction over Pt/Ba/CeO2 catalysts

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

A DFT study of the NO dissociation on gold surfaces doped with transition metals

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