An energy descriptor to quantify methane selectivity in Fischer-Tropsch synthesis: A density functional theory study

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

*Corresponding author for this work

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

Selectivity is a fundamental issue in heterogeneous catalysis. In this study, the CH(4) selectivity in Fischer-Tropsch synthesis is chosen to be investigated: CH4 selectivity on Rh, Co, Ru, Fe, and Re surfaces is computed by first-principles methods. In conjunction with kinetic analyses, we are able to derive the effective barrier difference between methane formation and chain growth (Delta E(eff)) to quantify the CH(4) selectivity. By using this energy descriptor, the ranking of methane selectivity predicted from density functional theory (DFT) calculations is consistent with experimental work. Moreover, a linear correlation between Delta E(eff) and the chemisorption energy of C + 4H (Delta H) is found. This fundamental finding possesses the following significance: (i) it shows that the selectivity, which appears to have kinetic characteristics, is largely determined by thermodynamic properties; and (ii) it suggests that an increase of the binding strength of C + 4H will suppress methane selectivity.

Original languageEnglish
Pages (from-to)8858-8863
Number of pages6
JournalThe Journal of Physical Chemistry C
Volume113
Issue number20
Early online date29 Apr 2009
DOIs
Publication statusPublished - 21 May 2009

Keywords

  • supported cobalt catalysts
  • Evans-Polanyi relation
  • heterogeneous catalysis
  • synthesis gas
  • CO oxidation
  • chain growth
  • hydrocarbon synthesis
  • manganese oxide
  • H2-CO mixtures
  • group-8 metals

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