NO reduction with CO in the presence and absence of H2O over Pd/γ-Al2O3 and Pd-VOx/γ-Al2O3 catalysts: The formation of HNCO, NH3 and stable surface species

Neyertz, Claudia A.; Volpe, María Alicia; Pérez, Damián Eduardo; Costilla, Ignacio Oscar; Sánchez, Miguel; Gigola, Carlos Eugenio

doi:10.1016/j.apcata.2009.08.023

Cited by 30 publications

(19 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the currently-reported technologies of NO x abatement, the reduction of NO by CO occurring over three-way catalysts (TWCs) has attracted tremendous attention due to the simultaneous conversion of CO and NO. Noble metal catalysts (Rh, Pt and Pd) have been used in the reaction of NO + CO [2][3][4][5][6][7][8][9], due to their high activity and selectivity for NO reduction. Because of the scarcity and high price of Rh, Pt has been considered to be a better catalytic candidate for the catalytic reduction of NO.…”

Section: Introductionmentioning

confidence: 99%

Effect of Surface Copper Species on NO + CO Reaction over xCuO-Ce0.9Zr0.1O2 Catalysts: In Situ DRIFTS Studies

Yuan

et al. 2016

Catalysts

View full text Add to dashboard Cite

Abstract:In this work, the activity of xCuO-Ce 0.9 Zr 0.1 O 2 catalysts for the reaction of NO + CO was investigated. Especially, in situ DRIFTS was applied to investigate the surface species under the adsorption of NO and/or CO and the reaction of NO and CO to understand the key intermediates species and reaction process of NO + CO. The results suggest that the copper oxide species are well dispersed on the surface of the catalysts, which can be easily reduced to form Cu + species. The Cu + species are proposed to be important activity species. The results of this work also suggest that N 2 O 2 2− is likely an intermediate species that plays an important role in NO reduction by CO. Thus, more Cu + and highly dispersed copper oxide species are expected to be beneficial for the reaction of CO + NO over the xCuO-Ce 0.9 Zr 0.1 O 2 catalysts.

show abstract

Section: Introductionmentioning

confidence: 99%

Effect of Surface Copper Species on NO + CO Reaction over xCuO-Ce0.9Zr0.1O2 Catalysts: In Situ DRIFTS Studies

Yuan

et al. 2016

Catalysts

View full text Add to dashboard Cite

show abstract

“…[4][5][6] Nitric oxide has an odd number of electrons and is one of the most versatile molecules, making its chemistry and adsorption process of particular interest. 13 The adsorption of NO on the supported catalyst surface has been investigated by both experimental 7,[14][15][16][17][18][19][20] and theoretical procedures. [21][22][23][24][25][26][27][28][29] NO adsorbs on small Pd clusters through its nitrogen atom in a tilted orientation, preferentially in the hcp threefold and bridge sites, 27 although the relative binding energies are strongly dependent on the size and geometry of the cluster employed.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Gamma-Al₂O₃Support on the NO Adsorption on Pd₄Cluster

Prates¹,

Ferreira²,

Carneiro³

et al. 2016

Journal of the Brazilian Chemical Society

View full text Add to dashboard Cite

The effect of γ-Al 2 O 3 support on the NO adsorption on Pd 4 clusters was investigated by means of density functional theory (DFT) calculations. Pd 4 adsorbed on γ-Al 2 O 3 (represented by a Al 14 O 24 H 6 cluster) changes its preferential geometry from tetrahedral to a distorted planar structure. The alumina support promotes a higher dispersion in the palladium catalyst and reduces the NO adsorption energy to -25.6 kcal mol -1 (computed at B3LYP/LANL2DZ/6-311+G(d)), in close agreement with the experimental value of -27.2 kcal mol . Charge density analysis show that the electron flux between the NO molecule and Pd 4 depends on the adsorption form, with back-donation being stronger in the bridge adsorption mode.Keywords: Pd clusters, DFT, supported-Pd clusters, alumina, NO adsorption, back-donation IntroductionPalladium catalysts have found wide appllication in several areas of chemistry. [1][2][3] One of the most common and established use of palladium catalyst is to control automobile exhaust gas emission. [4][5][6] Use of catalytic converter in automobile exhaust is a requirement to reach the recommended limits for emission of toxic byproducts. Although studies have been dedicated to the understanding of the catalytic conversion process in the exhaust emission, 7 more fundamental studies are still necessary for a full comprehension of the catalytic process, particularly at the molecular level. 8,9 Commonly, the platinum and palladium catalysts are supported on metal oxides, among them γ-Al 2 O 3 , although oxides of cerium, zirconium and titanium are also frequently employed. [10][11][12] These supported catalysts are thus employed to remove carbon monoxide (CO), nitric oxide (NO), NO x and SO x contaminants, among others, from the exhaust engine. [4][5][6] Nitric oxide has an odd number of electrons and is one of the most versatile molecules, making its chemistry and adsorption process of particular interest. 13 The adsorption of NO on the supported catalyst surface has been investigated by both experimental 7,14-20 and theoretical procedures. [21][22][23][24][25][26][27][28][29] NO adsorbs on small Pd clusters through its nitrogen atom in a tilted orientation, preferentially in the hcp threefold and bridge sites, 27 although the relative binding energies are strongly dependent on the size and geometry of the cluster employed. 27 For adsorption of NO on an extended surface at low coverage the interaction is determined by electron donation and back-donation involving the 5σ/2π* antibonding orbital of the NO molecule and the d-bands of the transition metal, with a net charge transfer from the transition metal to the adsorbed NO. 29 However, the extent of the interaction via the back-donation process is strongly dependent on the coordination mode of the NO molecule. On a flat surface, the preferential adsorption occurs on a hollow-site. 29 Adsorption on the energetically less favorable top-site results in tilted orientation with the NO bent to the metal surface.In the vast literature on theoretical studies of N...

show abstract

“…However, since there is no CO present in the feed, this suggestion can be ruled out. Other species reported to be present at this wavenumber include NO þ ions adsorbed on Al 2 O 3 supported catalysts [15,16] and also gaseous N 2 O [17,18]. During low-temperature reaction, we observe in Fig.…”

Section: Resultsmentioning

confidence: 85%

Passive SCR: The Effect of H $$_2$$ 2 to NO Ratio on the Formation of NH $$_3$$ 3 Over Alumina Supported Platinum and Palladium Catalysts

et al. 2016

View full text Add to dashboard Cite

We investigate the relationship between the H 2 :NO ratio and NH 3 formation over alumina supported Pt and Pd catalysts. By kinetic studies and in situ infrared spectroscopy, we report that NH 3 formation is not only sensitive to the catalyst formulation but equally dependent on the feed gas composition and temperature. Specifically, we identify that hydrogen plays an important role in the dissociation of NO at low temperature. We also show that the support material itself plays a vital role in the ammonia formation mechanism due to the redox behaviour of NO adsorption at low temperature. This was unexpected as the noble metal is generally considered to be the active phase for the reaction of NO and H 2 .

show abstract

NO reduction with CO in the presence and absence of H2O over Pd/γ-Al2O3 and Pd-VOx/γ-Al2O3 catalysts: The formation of HNCO, NH3 and stable surface species

Cited by 30 publications

References 52 publications

Effect of Surface Copper Species on NO + CO Reaction over xCuO-Ce0.9Zr0.1O2 Catalysts: In Situ DRIFTS Studies

Effect of Surface Copper Species on NO + CO Reaction over xCuO-Ce0.9Zr0.1O2 Catalysts: In Situ DRIFTS Studies

The Effect of Gamma-Al₂O₃Support on the NO Adsorption on Pd₄Cluster

Passive SCR: The Effect of H $$_2$$ 2 to NO Ratio on the Formation of NH $$_3$$ 3 Over Alumina Supported Platinum and Palladium Catalysts

Contact Info

Product

Resources

About

NO reduction with CO in the presence and absence of H2O over Pd/γ-Al2O3 and Pd-VOx/γ-Al2O3 catalysts: The formation of HNCO, NH3 and stable surface species

Cited by 30 publications

References 52 publications

Effect of Surface Copper Species on NO + CO Reaction over xCuO-Ce0.9Zr0.1O2 Catalysts: In Situ DRIFTS Studies

Effect of Surface Copper Species on NO + CO Reaction over xCuO-Ce0.9Zr0.1O2 Catalysts: In Situ DRIFTS Studies

The Effect of Gamma-Al2O3Support on the NO Adsorption on Pd4Cluster

Passive SCR: The Effect of H $$_2$$ 2 to NO Ratio on the Formation of NH $$_3$$ 3 Over Alumina Supported Platinum and Palladium Catalysts

Contact Info

Product

Resources

About

The Effect of Gamma-Al₂O₃Support on the NO Adsorption on Pd₄Cluster