Tandem promotion of iron catalysts by sodium-sulfur and nitrogen-doped carbon layers on carbon nanotube supports for the Fischer-Tropsch to olefins synthesis

Sandy M.G. Lama, J. Lennart Weber, Tobias Heil, Jan P. Hofmann, Runyu Yan, Krijn P. de Jong, Martin Oschatz

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15 Citations (Scopus)
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Abstract

Carbon nanotubes with various surface modifications are utilized as supports for iron species and the resulting catalysts are used for the Fischer-Tropsch synthesis of C2–C4 olefins with and without the addition of Na and S promoters. A layer of nitrogen-doped carbon on the carbon nanotube surface serves as an efficient promoter independent of the presence of Na/S. It leads to significantly faster catalyst activation as compared to the tubes without such a layer resulting from an electronic junction effect at the iron-support interface. The tandem of Na/S- plus N-doped carbon promoted catalysts provide a record high iron-time-yield of up to 94∙10−5molCO gFe -1 s-1 under industrially relevant Fischer-Tropsch conditions (340 °C, 10 bar, H2/CO = 2) and slow deactivation over more than 185 h of time on stream. Furthermore, this tandem promotion leads to enhanced C2–C4 olefin and C5+ selectivity along with reduced methanization as compared to the solely Na/S-promoted catalysts.

Original languageEnglish
Pages (from-to)213-220
Number of pages8
JournalApplied Catalysis. A, General
Volume568
DOIs
Publication statusPublished - 25 Nov 2018

Funding

S.M.G.L. and M.O. gratefully acknowledge financial support by the Max Planck Society . We thank Dr. Nadja Tarakina and Heike Runge for help with the electron microscopy experiments. Appendix A

Keywords

  • C–C olefins
  • Carbon supports
  • Electronic junction
  • Fischer-Tropsch synthesis
  • Iron catalysts

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