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Title: Binding and activation of ethylene on tungsten carbide and platinum surfaces

Abstract

In this paper, 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 C 2H 4 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 C 2H 4 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 C=C bond, the surfacemore » 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. Finally, these results pave the way to address further experimental and theoretical studies focused on the hydrogenation of ethylene and more complex unsaturated hydrocarbons.« less

Authors:
ORCiD logo [1];  [1]; ORCiD logo [2]; ORCiD logo [3]
  1. Universidad de Medellín (Columbia)
  2. Univ. of Sydney, NSW (Australia)
  3. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1546046
Alternate Identifier(s):
OSTI ID: 1545402
Report Number(s):
BNL-211916-2019-JAAM
Journal ID: ISSN 1463-9076; PPCPFQ
Grant/Contract Number:  
SC0012704
Resource Type:
Accepted Manuscript
Journal Name:
Physical Chemistry Chemical Physics. PCCP (Print)
Additional Journal Information:
Journal Name: Physical Chemistry Chemical Physics. PCCP (Print); Journal ID: ISSN 1463-9076
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY

Citation Formats

Jimenez-Orozco, Carlos, Flórez, Elizabeth, Montoya, Alejandro, and Rodriguez, Jose A. Binding and activation of ethylene on tungsten carbide and platinum surfaces. United States: N. p., 2019. Web. doi:10.1039/C9CP03214B.
Jimenez-Orozco, Carlos, Flórez, Elizabeth, Montoya, Alejandro, & Rodriguez, Jose A. Binding and activation of ethylene on tungsten carbide and platinum surfaces. United States. doi:10.1039/C9CP03214B.
Jimenez-Orozco, Carlos, Flórez, Elizabeth, Montoya, Alejandro, and Rodriguez, Jose A. Mon . "Binding and activation of ethylene on tungsten carbide and platinum surfaces". United States. doi:10.1039/C9CP03214B.
@article{osti_1546046,
title = {Binding and activation of ethylene on tungsten carbide and platinum surfaces},
author = {Jimenez-Orozco, Carlos and Flórez, Elizabeth and Montoya, Alejandro and Rodriguez, Jose A.},
abstractNote = {In this paper, 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 C=C 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. Finally, these results pave the way to address further experimental and theoretical studies focused on the hydrogenation of ethylene and more complex unsaturated hydrocarbons.},
doi = {10.1039/C9CP03214B},
journal = {Physical Chemistry Chemical Physics. PCCP (Print)},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {7}
}

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Works referenced in this record:

Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set
journal, October 1996


From ultrasoft pseudopotentials to the projector augmented-wave method
journal, January 1999


Special points for Brillouin-zone integrations
journal, June 1976

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