Binding and activation of ethylene on tungsten carbide and platinum surfaces

Carlos Jimenez-Orozco, Elizabeth Flórez, Alejandro Montoya, Jose A. Rodriguez

Resultado de la investigación: Contribución a una revistaArtículoInvestigaciónrevisión exhaustiva

Resumen

Density functional calculations were used to evaluate the ability of cubic and hexagonal phases of tungsten carbide to bind ethylene, as a model compound of unsaturated hydrocarbons, since its adsorption is the first step in important catalytic processes. The calculations give the following trend in stability: α-WC(0001)-C > α-WC(0001)-W > Pt(111) > γ-WC(001), with the binding energy varying in the range of -0.72 to -2.91 eV. The sub-surface layers play a crucial role in the binding, favoring a charge reorganization at extended ranges (above 6 Å) from bulk towards the surface, however, the electronic structure of the surface was modified only in the topmost layer. The surface sites for geometric C2H4 activation were identified, leading to a surface distortion due to an upwards shifting of surface atoms in the range 0.13-0.61 Å observed in Pt(111), α-WC(0001)-C, and γ-WC(001), with distortion energies of 0.13, 0.15 and 0.61 eV, respectively. The activation of C2H4 on tungsten carbides was compared with other transition metal carbide surfaces, which leads to a general classification of the elongation of carbon-carbon bond into a set of only three groups. If the interest is to activate ethylene CC bond, the surface sites and the binding modes should be those of the groups II and III. The infrared spectra show mainly four useful signals as a fingerprint to support and complement future experiments. The results of this work indicate that the α-WC-W surface could be directly responsible for the catalytic performance, while the binding of olefins on α-WC-C could cause surface poisoning. The metastable γ-WC(001) surface could be a promising system as compared to the known α-WC(0001) surface, but challenges arise regarding its synthesis, stability and catalytic performance. These results pave the way to address further experimental and theoretical studies focused on the hydrogenation of ethylene and more complex unsaturated hydrocarbons.

Idioma originalInglés
Páginas (desde-hasta)17332-17342
Número de páginas11
PublicaciónPhysical Chemistry Chemical Physics
Volumen21
N.º31
DOI
EstadoPublicada - 1 ene 2019

Huella dactilar

tungsten carbides
Platinum
platinum
ethylene
Chemical activation
activation
Hydrocarbons
hydrocarbons
tungsten carbide
surface distortion
Carbon
carbon
poisoning
carbides
complement
alkenes
elongation
hydrogenation
Alkenes
Binding energy

Citar esto

Jimenez-Orozco, Carlos ; Flórez, Elizabeth ; Montoya, Alejandro ; Rodriguez, Jose A. / Binding and activation of ethylene on tungsten carbide and platinum surfaces. En: Physical Chemistry Chemical Physics. 2019 ; Vol. 21, N.º 31. pp. 17332-17342.
@article{88a7769c52b945c28745a8b2841c5a77,
title = "Binding and activation of ethylene on tungsten carbide and platinum surfaces",
abstract = "Density functional calculations were used to evaluate the ability of cubic and hexagonal phases of tungsten carbide to bind ethylene, as a model compound of unsaturated hydrocarbons, since its adsorption is the first step in important catalytic processes. The calculations give the following trend in stability: α-WC(0001)-C > α-WC(0001)-W > Pt(111) > γ-WC(001), with the binding energy varying in the range of -0.72 to -2.91 eV. The sub-surface layers play a crucial role in the binding, favoring a charge reorganization at extended ranges (above 6 {\AA}) from bulk towards the surface, however, the electronic structure of the surface was modified only in the topmost layer. The surface sites for geometric C2H4 activation were identified, leading to a surface distortion due to an upwards shifting of surface atoms in the range 0.13-0.61 {\AA} observed in Pt(111), α-WC(0001)-C, and γ-WC(001), with distortion energies of 0.13, 0.15 and 0.61 eV, respectively. The activation of C2H4 on tungsten carbides was compared with other transition metal carbide surfaces, which leads to a general classification of the elongation of carbon-carbon bond into a set of only three groups. If the interest is to activate ethylene CC bond, the surface sites and the binding modes should be those of the groups II and III. The infrared spectra show mainly four useful signals as a fingerprint to support and complement future experiments. The results of this work indicate that the α-WC-W surface could be directly responsible for the catalytic performance, while the binding of olefins on α-WC-C could cause surface poisoning. The metastable γ-WC(001) surface could be a promising system as compared to the known α-WC(0001) surface, but challenges arise regarding its synthesis, stability and catalytic performance. These results pave the way to address further experimental and theoretical studies focused on the hydrogenation of ethylene and more complex unsaturated hydrocarbons.",
author = "Carlos Jimenez-Orozco and Elizabeth Fl{\'o}rez and Alejandro Montoya and Rodriguez, {Jose A.}",
year = "2019",
month = "1",
day = "1",
doi = "10.1039/c9cp03214b",
language = "Ingl{\'e}s",
volume = "21",
pages = "17332--17342",
journal = "Physical Chemistry Chemical Physics",
issn = "1463-9076",
publisher = "Royal Society of Chemistry",
number = "31",

}

Binding and activation of ethylene on tungsten carbide and platinum surfaces. / Jimenez-Orozco, Carlos; Flórez, Elizabeth; Montoya, Alejandro; Rodriguez, Jose A.

En: Physical Chemistry Chemical Physics, Vol. 21, N.º 31, 01.01.2019, p. 17332-17342.

Resultado de la investigación: Contribución a una revistaArtículoInvestigaciónrevisión exhaustiva

TY - JOUR

T1 - Binding and activation of ethylene on tungsten carbide and platinum surfaces

AU - Jimenez-Orozco, Carlos

AU - Flórez, Elizabeth

AU - Montoya, Alejandro

AU - Rodriguez, Jose A.

PY - 2019/1/1

Y1 - 2019/1/1

N2 - Density functional calculations were used to evaluate the ability of cubic and hexagonal phases of tungsten carbide to bind ethylene, as a model compound of unsaturated hydrocarbons, since its adsorption is the first step in important catalytic processes. The calculations give the following trend in stability: α-WC(0001)-C > α-WC(0001)-W > Pt(111) > γ-WC(001), with the binding energy varying in the range of -0.72 to -2.91 eV. The sub-surface layers play a crucial role in the binding, favoring a charge reorganization at extended ranges (above 6 Å) from bulk towards the surface, however, the electronic structure of the surface was modified only in the topmost layer. The surface sites for geometric C2H4 activation were identified, leading to a surface distortion due to an upwards shifting of surface atoms in the range 0.13-0.61 Å observed in Pt(111), α-WC(0001)-C, and γ-WC(001), with distortion energies of 0.13, 0.15 and 0.61 eV, respectively. The activation of C2H4 on tungsten carbides was compared with other transition metal carbide surfaces, which leads to a general classification of the elongation of carbon-carbon bond into a set of only three groups. If the interest is to activate ethylene CC bond, the surface sites and the binding modes should be those of the groups II and III. The infrared spectra show mainly four useful signals as a fingerprint to support and complement future experiments. The results of this work indicate that the α-WC-W surface could be directly responsible for the catalytic performance, while the binding of olefins on α-WC-C could cause surface poisoning. The metastable γ-WC(001) surface could be a promising system as compared to the known α-WC(0001) surface, but challenges arise regarding its synthesis, stability and catalytic performance. These results pave the way to address further experimental and theoretical studies focused on the hydrogenation of ethylene and more complex unsaturated hydrocarbons.

AB - Density functional calculations were used to evaluate the ability of cubic and hexagonal phases of tungsten carbide to bind ethylene, as a model compound of unsaturated hydrocarbons, since its adsorption is the first step in important catalytic processes. The calculations give the following trend in stability: α-WC(0001)-C > α-WC(0001)-W > Pt(111) > γ-WC(001), with the binding energy varying in the range of -0.72 to -2.91 eV. The sub-surface layers play a crucial role in the binding, favoring a charge reorganization at extended ranges (above 6 Å) from bulk towards the surface, however, the electronic structure of the surface was modified only in the topmost layer. The surface sites for geometric C2H4 activation were identified, leading to a surface distortion due to an upwards shifting of surface atoms in the range 0.13-0.61 Å observed in Pt(111), α-WC(0001)-C, and γ-WC(001), with distortion energies of 0.13, 0.15 and 0.61 eV, respectively. The activation of C2H4 on tungsten carbides was compared with other transition metal carbide surfaces, which leads to a general classification of the elongation of carbon-carbon bond into a set of only three groups. If the interest is to activate ethylene CC bond, the surface sites and the binding modes should be those of the groups II and III. The infrared spectra show mainly four useful signals as a fingerprint to support and complement future experiments. The results of this work indicate that the α-WC-W surface could be directly responsible for the catalytic performance, while the binding of olefins on α-WC-C could cause surface poisoning. The metastable γ-WC(001) surface could be a promising system as compared to the known α-WC(0001) surface, but challenges arise regarding its synthesis, stability and catalytic performance. These results pave the way to address further experimental and theoretical studies focused on the hydrogenation of ethylene and more complex unsaturated hydrocarbons.

UR - http://www.scopus.com/inward/record.url?scp=85070704004&partnerID=8YFLogxK

U2 - 10.1039/c9cp03214b

DO - 10.1039/c9cp03214b

M3 - Artículo

VL - 21

SP - 17332

EP - 17342

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

SN - 1463-9076

IS - 31

ER -