A first-principles study of oxygenates on Co surfaces in Fischer-Tropsch synthesis

Jun Cheng, P. Hu*, Peter Ellis, Sam French, Gordon Kelly, C. Martin Lok

*Corresponding author for this work

Research output: Contribution to journalArticle

64 Citations (Scopus)

Abstract

Extensive density function theory calculations are performed to study the mechanism of the formation of aldehyde and alcohol on Co surfaces in Fischer-Tropsch synthesis, a challenging issue in heterogeneous catalysis. Three possible pathways for the production of formaldehyde and methanol on flat and stepped Co(0001) surfaces are investigated: (i) CO + 4H -> CHO + 3H -> CH2O + 2H -> CH3O + H -> CH3OH; (ii) CO + 4H -> COH + 3H -> CHOH + 2H -> CH2OH + H -> CH3OH; and (iii) the coupling reactions of CH2 + O -> CH2O and CH3 + OH -> CH3OH. It is found that these pathways are generally favored at step sites, and the preferred mechanism is pathway (i) via CHO. Furthermore, the three traditional chain growth mechanisms in Fischer-Tropsch synthesis are semi quantitatively compared and discussed. Our results suggest that the two mechanisms involving oxygenate intermediates (the CO-insertion and hydroxycarbene mechanisms) are less important than the carbene mechanism in the production of long chain hydrocarbons. However, the CO-insertion mechanism may be responsible for the production of long-chain oxygenates.

Original languageEnglish
Pages (from-to)9464-9473
Number of pages10
JournalThe Journal of Physical Chemistry C
Volume112
Issue number25
Early online date4 Jun 2008
DOIs
Publication statusPublished - 26 Jun 2008

Keywords

  • density-functional theory
  • gas shift kinetics
  • methanol decomposition
  • hydrocarbon synthesis
  • cobalt catalysts
  • metal-surfaces
  • chain growth
  • PT(111)
  • mechanism
  • adsorption

Cite this

A first-principles study of oxygenates on Co surfaces in Fischer-Tropsch synthesis. / Cheng, Jun; Hu, P.; Ellis, Peter; French, Sam; Kelly, Gordon; Lok, C. Martin.

In: The Journal of Physical Chemistry C, Vol. 112, No. 25, 26.06.2008, p. 9464-9473.

Research output: Contribution to journalArticle

Cheng, J, Hu, P, Ellis, P, French, S, Kelly, G & Lok, CM 2008, 'A first-principles study of oxygenates on Co surfaces in Fischer-Tropsch synthesis', The Journal of Physical Chemistry C, vol. 112, no. 25, pp. 9464-9473. https://doi.org/10.1021/jp802242t
Cheng, Jun ; Hu, P. ; Ellis, Peter ; French, Sam ; Kelly, Gordon ; Lok, C. Martin. / A first-principles study of oxygenates on Co surfaces in Fischer-Tropsch synthesis. In: The Journal of Physical Chemistry C. 2008 ; Vol. 112, No. 25. pp. 9464-9473.
@article{6a6c80921af642f0949585ce9c4b156f,
title = "A first-principles study of oxygenates on Co surfaces in Fischer-Tropsch synthesis",
abstract = "Extensive density function theory calculations are performed to study the mechanism of the formation of aldehyde and alcohol on Co surfaces in Fischer-Tropsch synthesis, a challenging issue in heterogeneous catalysis. Three possible pathways for the production of formaldehyde and methanol on flat and stepped Co(0001) surfaces are investigated: (i) CO + 4H -> CHO + 3H -> CH2O + 2H -> CH3O + H -> CH3OH; (ii) CO + 4H -> COH + 3H -> CHOH + 2H -> CH2OH + H -> CH3OH; and (iii) the coupling reactions of CH2 + O -> CH2O and CH3 + OH -> CH3OH. It is found that these pathways are generally favored at step sites, and the preferred mechanism is pathway (i) via CHO. Furthermore, the three traditional chain growth mechanisms in Fischer-Tropsch synthesis are semi quantitatively compared and discussed. Our results suggest that the two mechanisms involving oxygenate intermediates (the CO-insertion and hydroxycarbene mechanisms) are less important than the carbene mechanism in the production of long chain hydrocarbons. However, the CO-insertion mechanism may be responsible for the production of long-chain oxygenates.",
keywords = "density-functional theory, gas shift kinetics, methanol decomposition, hydrocarbon synthesis, cobalt catalysts, metal-surfaces, chain growth, PT(111), mechanism, adsorption",
author = "Jun Cheng and P. Hu and Peter Ellis and Sam French and Gordon Kelly and Lok, {C. Martin}",
year = "2008",
month = "6",
day = "26",
doi = "10.1021/jp802242t",
language = "English",
volume = "112",
pages = "9464--9473",
journal = "The Journal of Physical Chemistry C",
issn = "1932-7447",
publisher = "American Chemical Society",
number = "25",

}

TY - JOUR

T1 - A first-principles study of oxygenates on Co surfaces in Fischer-Tropsch synthesis

AU - Cheng, Jun

AU - Hu, P.

AU - Ellis, Peter

AU - French, Sam

AU - Kelly, Gordon

AU - Lok, C. Martin

PY - 2008/6/26

Y1 - 2008/6/26

N2 - Extensive density function theory calculations are performed to study the mechanism of the formation of aldehyde and alcohol on Co surfaces in Fischer-Tropsch synthesis, a challenging issue in heterogeneous catalysis. Three possible pathways for the production of formaldehyde and methanol on flat and stepped Co(0001) surfaces are investigated: (i) CO + 4H -> CHO + 3H -> CH2O + 2H -> CH3O + H -> CH3OH; (ii) CO + 4H -> COH + 3H -> CHOH + 2H -> CH2OH + H -> CH3OH; and (iii) the coupling reactions of CH2 + O -> CH2O and CH3 + OH -> CH3OH. It is found that these pathways are generally favored at step sites, and the preferred mechanism is pathway (i) via CHO. Furthermore, the three traditional chain growth mechanisms in Fischer-Tropsch synthesis are semi quantitatively compared and discussed. Our results suggest that the two mechanisms involving oxygenate intermediates (the CO-insertion and hydroxycarbene mechanisms) are less important than the carbene mechanism in the production of long chain hydrocarbons. However, the CO-insertion mechanism may be responsible for the production of long-chain oxygenates.

AB - Extensive density function theory calculations are performed to study the mechanism of the formation of aldehyde and alcohol on Co surfaces in Fischer-Tropsch synthesis, a challenging issue in heterogeneous catalysis. Three possible pathways for the production of formaldehyde and methanol on flat and stepped Co(0001) surfaces are investigated: (i) CO + 4H -> CHO + 3H -> CH2O + 2H -> CH3O + H -> CH3OH; (ii) CO + 4H -> COH + 3H -> CHOH + 2H -> CH2OH + H -> CH3OH; and (iii) the coupling reactions of CH2 + O -> CH2O and CH3 + OH -> CH3OH. It is found that these pathways are generally favored at step sites, and the preferred mechanism is pathway (i) via CHO. Furthermore, the three traditional chain growth mechanisms in Fischer-Tropsch synthesis are semi quantitatively compared and discussed. Our results suggest that the two mechanisms involving oxygenate intermediates (the CO-insertion and hydroxycarbene mechanisms) are less important than the carbene mechanism in the production of long chain hydrocarbons. However, the CO-insertion mechanism may be responsible for the production of long-chain oxygenates.

KW - density-functional theory

KW - gas shift kinetics

KW - methanol decomposition

KW - hydrocarbon synthesis

KW - cobalt catalysts

KW - metal-surfaces

KW - chain growth

KW - PT(111)

KW - mechanism

KW - adsorption

U2 - 10.1021/jp802242t

DO - 10.1021/jp802242t

M3 - Article

VL - 112

SP - 9464

EP - 9473

JO - The Journal of Physical Chemistry C

JF - The Journal of Physical Chemistry C

SN - 1932-7447

IS - 25

ER -