Fischer-Tropsch synthesis: Deuterium kinetic isotope study for hydrogenation of carbon oxides over cobalt and iron catalysts

Muthu Kumaran Gnanamani, Gary Jacobs, Wilson D. Shafer, Dennis Sparks, Burtron H. Davis

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

The hydrogenation of CO2 using Pt promoted Co/γ-Al 2O3 and doubly (Cu, K) promoted iron catalysts exhibits an inverse isotope effect (rH/rD < 1). The observed inverse isotope effect for hydrogenation of CO2 shows that hydrogen addition to CO2 should be involved in the kinetically relevant step. The systematic increase of inverse isotope effect with carbon number of products obtained during H2-D2-H2 switching experiments suggests the possible existence of a common intermediate (CH x O) for hydrogenation of CO2 over both cobalt and iron FT catalysts. The magnitude of the inverse isotope effect is lower for CO2 compared to CO hydrogenation under similar reaction conditions. The deuterium isotope effect does not provide a definite conclusion regarding the mechanism which CO 2 hydrogenation follows (alkyl, enol, or alkylidine mechanisms).

Original languageEnglish
Pages (from-to)1420-1428
Number of pages9
JournalCatalysis Letters
Volume141
Issue number10
DOIs
StatePublished - Oct 2011

Keywords

  • CO insertion mechanism
  • Cobalt
  • Enol mechanism
  • High alpha Fe
  • Hydrogenation of carbon oxides
  • Inverse isotope effect
  • Low alpha Fe: alkyl mechanism

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry

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