Selectivity control of Cu promoted iron-based Fischer-Tropsch catalyst by tuning the oxidation state of Cu to mimic K

Venkat Ramana Rao Pendyala, Gary Jacobs, Muthu Kumaran Gnanamani, Yongfeng Hu, Aimee Maclennan, Burtron H. Davis

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

The effect of activation gas on the Fischer-Tropsch synthesis (FTS) performance of copper and potassium promoted precipitated iron-based catalysts was investigated in an earlier study [Catal. Lett. 144 (2014) 1624-1635]. In that study, CO and syngas (H2/CO = 0.7) activation methods were tested after varying the copper promoter loading (0, 2, and 5%, atomic ratios relative to iron). At similar CO conversion level, the selectivities for the CO-activated catalysts were identical for the various copper loaded catalysts, whereas for the syngas activated catalysts, light hydrocarbon (methane and C2-C4) selectivities decreased and higher hydrocarbon (C5+) selectivities increased with increasing copper loading. To understand the reason for that behavior, the catalyst samples were characterized by XANES/EXAFS spectroscopy following each activation procedure before and after exposure to FTS conditions. Cu K-edge normalized XANES results indicate that for the syngas activated catalyst copper is present primarily in the Cu1+ state, whereas for CO activated catalyst the copper is more reduced (greater fraction in the Cu0 state). The Cu1+ in the syngas activated catalyst behaved like K1+; therefore, the C5+ selectivity was enhanced and light hydrocarbon selectivity was suppressed.

Original languageEnglish
Pages (from-to)45-53
Number of pages9
JournalApplied Catalysis A: General
Volume495
DOIs
StatePublished - Apr 5 2015

Bibliographical note

Funding Information:
This work is supported by the University of Wyoming contract number 1001541-Davis and the Commonwealth of Kentucky . EXAFS/XANES described in this paper was performed in part at the Canadian Light Source, which is funded by the Canada Foundation for Innovation , the Natural Sciences and Engineering Research Council of Canada , the National Research Council Canada , the Canadian Institutes of Health Research , the Government of Saskatchewan , Western Economic Diversification Canada , and the University of Saskatchewan .

Publisher Copyright:
© 2015 Elsevier B.V. All rights reserved.

Keywords

  • Activation gas
  • Cu oxidation state
  • Fischer-Tropsch synthesis
  • Iron-based catalyst
  • Product selectivity
  • XANES/EXAFS

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology

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