1887
banner image
No data available.
Please log in to see this content.
You have no subscription access to this content.
No metrics data to plot.
The attempt to load metrics for this article has failed.
The attempt to plot a graph for these metrics has failed.
Elementary steps of the catalytic NOx reduction with NH3: Cluster studies on adsorbate diffusion and dehydrogenation at vanadium oxide substrate
Rent:
Rent this article for
USD
10.1063/1.4804160
/content/aip/journal/jcp/138/19/10.1063/1.4804160
http://aip.metastore.ingenta.com/content/aip/journal/jcp/138/19/10.1063/1.4804160

Figures

Image of FIG. 1.
FIG. 1.

Cluster models used to evaluate (a) a specific surface NH diffusion path, VOH, and (b) the path of O(3) oxygen diffusing to a neighboring O(3) vacancy site, VOH. Vanadium atoms are shown by large yellow, oxygen by smaller red, and saturating hydrogen by very small gray balls. Note that oxygen O(1) is hidden under a vanadium atom. The black dot in Fig. 1(b) denotes an oxygen vacancy O(3). Corresponding oxygen and vanadium sites are labeled accordingly.

Image of FIG. 2.
FIG. 2.

Diffusion paths and corresponding energetics for diffusion of atomic hydrogen at the perfect VO(010) surface. Vanadium atoms are shown by large yellow and oxygen by smaller red balls. The diffusion paths of the three regions, ridge, slope, and valley, are indicated by black lines between equilibrium positions A, B, … K denoted by filled dots and transition state positions shown by open circles. At the bottom relative binding energies of hydrogen for the equilibrium and transition state sites along the paths are shown, see text.

Image of FIG. 3.
FIG. 3.

Initial, transition, and final state geometries for hydrogen diffusion paths (a) B → C (ridge), (b) E → F (valley), and (c) G → H (slope). Vanadium atoms are shown by large yellow, oxygen by smaller red balls, and hydrogen by small blue balls. The diffusion directions are indicated by blue arrows.

Image of FIG. 4.
FIG. 4.

Initial, transition, and final state geometries for surface HO formation starting with two OH groups at neighboring O(1) sites. Vanadium atoms are shown by large yellow, oxygen by smaller red balls, and hydrogen by small blue balls.

Image of FIG. 5.
FIG. 5.

Diffusion paths and corresponding energetics for diffusion of NH at the perfect VO(010) surface. Vanadium atoms are shown by large yellow and oxygen by smaller red balls. The diffusion paths of the three regions, ridge, slope, and valley, are indicated by black lines between equilibrium positions A , B , C , D , E denoted by filled dots and transition state positions shown by open circles. At the bottom relative binding energies of NH for the equilibrium and transition state sites along the paths are shown, see text.

Image of FIG. 6.
FIG. 6.

(a) Initial, (b) transition, and (c) final state geometries for diffusive “tumble” motion of NH between positions A and B above neighboring O(1) sites at the ridge of the perfect VO(010) surface, see Fig. 5 . The three snapshots are shown for top and side views with respect to the surface. Vanadium atoms are shown by large yellow, oxygen by smaller red balls, and hydrogen by small blue balls. The diffusion directions are indicated by blue arrows.

Image of FIG. 7.
FIG. 7.

(a) Initial, (b) transition, and (c) final state geometries for diffusive “twist” motion of NH between positions B and C above neighboring O(1) sites at the ridge of the perfect VO(010) surface. The three snapshots are shown for top and side views with respect to the surface. Vanadium atoms are shown by large yellow, oxygen by smaller red balls, and hydrogen by small blue balls. The diffusion directions are indicated by blue arrows.

Image of FIG. 8.
FIG. 8.

Energetics of the diffusion of oxygen from an O(3) site to a neighboring vacancy site O(3). The figure includes initial (denoted O(3)/O(3)), transition, and final state geometries (denoted O(3)/O(3)) along the diffusion path. Vanadium atoms are shown by large yellow, oxygen by smaller red balls, and oxygen vacancy sites are indicated by small black dots. Parameters a, b (in Å) refer to distances between the diffusing oxygen and its vanadium neighbors.

Image of FIG. 9.
FIG. 9.

Energetics of the diffusion of sub-surface oxygen from an O(1) site to a neighboring vacancy site O(2). The figure includes initial, transition, and final state geometries along the diffusion path. Vanadium atoms are shown by large yellow, oxygen by smaller red balls, and oxygen vacancy sites are indicated by small black dots.

Image of FIG. 10.
FIG. 10.

Energy diagrams of NH, x = 0, 1, … 4, (de)hydrogenation from cluster calculations, see text. The diagrams are labeled accordingly and refer to reactions in gas phase (blue), at the VO(010) surface (black), and at the reduced VO(010) surface near oxygen vacancy sites O(1) (red), V/O(1) (purple dashed), O(2) (green), and O(3) (green dashed). All energies (in eV) are given relative to the value E (x = 3) of NH at the surface which is set to zero.

Tables

Generic image for table
Table I.

Energetics for hydrogen diffusion between different oxygen sites A … K at the VO(010) surface, see Fig. 2 . The pairs X, Y define diffusion paths between two oxygen sites O(1), O(2 ), or O(3 ) each as given in the Table. For each path of the ridge, slope, and valley region corresponding differences ΔE in adsorption energy and diffusion energies D for both path directions are listed, see text. All energies are shown in eV.

Generic image for table
Table II.

OH distances for hydrogen diffusion between different oxygen sites A … K at the VO(010) surface, see Fig. 2 . The pairs X, Y define diffusion paths between two oxygen sites O(1), O(2 ), or O(3 ) each as given in the table. For each path of the ridge, slope, and valley region corresponding OH distances d/d are listed for hydrogen adsorbed at X, the transition state, and hydrogen adsorbed at Y, see text. (Calculated gas phase values of d are 0.98 Å for free OH and 0.97 Å for free HO.) All distances in the table are given in Å.

Generic image for table
Table III.

Energetics for NH diffusion between different oxygen sites A … E at the VO(010) surface, see Fig. 5 . The pairs X, Y define diffusion paths between oxygen and vanadium sites O(1), O(2 ), or V each as given in the table. For each path of the ridge, slope, and valley region corresponding differences ΔE in adsorption energy and diffusion energies D for both path directions are listed, see text. All energies are shown in eV.

Generic image for table
Table IV.

Energetics for oxygen diffusion from one site to an adjacent vacancy, see text. Initial and final states are each characterized by pairs of oxygen and oxygen vacancy sites, see Fig. 1 . For each diffusion path corresponding differences ΔE in total energy and diffusion energies D for both path directions are listed, see text. All energies are shown in eV.

Generic image for table
Table V.

Experimental and calculated hydrogen binding energies, E(x), of NH, x = 1, … 4, in gas phase according to (5). The table includes results for the dissociation energy of the H molecule, E(H). All values are given in (eV).

Generic image for table
Table VI.

Reaction energies computed for the dehydrogenation reaction of NH, see text. The theoretical gas phase values, E (x) according to (7), are compared with values of E (x) according to (9) for the perfect VO(010) surface as well as for different oxygen vacancy sites of the reduced surface. All energies are given in (eV).

Loading

Article metrics loading...

/content/aip/journal/jcp/138/19/10.1063/1.4804160
2013-05-15
2014-04-23
Loading

Full text loading...

This is a required field
Please enter a valid email address
752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Elementary steps of the catalytic NOx reduction with NH3: Cluster studies on adsorbate diffusion and dehydrogenation at vanadium oxide substrate
http://aip.metastore.ingenta.com/content/aip/journal/jcp/138/19/10.1063/1.4804160
10.1063/1.4804160
SEARCH_EXPAND_ITEM