Effect of Phosphorus on the Activity and Stability of Supported Cobalt Catalysts for Fischer-Tropsch Synthesis

Michela Martinelli, Muthu Kumaran Gnanamani, Shelley D. Hopps, Dennis E. Sparks, Aimee MacLennan, Yongfeng Hu, Burtron H. Davis, Gary Jacobs

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Phosphorus promotion on Fischer-Tropsch (FT) synthesis was investigated for Co/Al2O3 and Co/SiO2 catalysts having the same Co/P ratio. When P is added to Co/Al2O3, CO conversion on a per g catalyst basis decreased, while methane selectivity increased. Catalyst stability was higher for the sample containing both P and Pt. The main cause for lower initial conversion is Co site blocking, while the lower extent of cobalt reduction for the P-promoted Co/Al2O3 sample played a lesser role. When SiO2 is used to support cobalt particles, an initial induction period for the P-promoted catalyst was observed, where CO conversion increased. Higher CO conversion at steady state, as well as improved catalyst stability during FT testing, suggest that P hindered sintering. Over the same period, a decline and leveling off of conversion were observed for the unpromoted catalyst. Completely different effects were observed depending on support type. P only acted as a poison for Co/Al2O3, whereas beneficial effects on steady state CO conversion and stability occurred with Co/SiO2. The different effects of P for Al2O3 and SiO2 supported Co catalysts can be explained by differences in Co-support interactions. With alumina, Co clusters are already stabilized by strong interactions with the support. P has no benefit, as it mainly interacts with alumina instead of Co; pore blocking by P also occurred. In contrast, SiO2 has weak interactions with Co and less Co cluster stabilization. With P promotion, P anchors Co to the support, improving Co dispersion, stability and steady-state conversion.

Original languageEnglish
Pages (from-to)3709-3716
Number of pages8
JournalChemCatChem
Volume10
Issue number17
DOIs
StatePublished - Sep 7 2018

Bibliographical note

Publisher Copyright:
© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Keywords

  • alumina
  • cobalt catalyst
  • Fischer-Tropsch synthesis
  • phosphorous
  • silica

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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