The role of carboxylic acid in cobalt Fischer-Tropsch synthesis catalyst deactivation

D. Kistamurthy (Corresponding author), A. M. Saib, D. J. Moodley, H. Preston, I. M. Ciobîcă, W. Janse van Rensburg, J.W. Niemantsverdriet, C. J. Weststrate

    Research output: Contribution to journalArticleAcademicpeer-review

    8 Citations (Scopus)

    Abstract

    Oxygenated compounds have previously been detected on spent Co/Al2O3FTS catalyst and have also been proposed to be precursors for carbon formation. Build-up of polymeric carbon on the catalyst during Fischer-Tropsch synthesis (FTS) can negatively influence activity over an extended reaction time. Adsorbed oxygenates detected on spent Co/γ-Al2O3FTS catalyst are deduced to be located on the γ-Al2O3support using attenuated total reflectance infrared spectroscopy (ATR-IR). The formation of a metal-carboxylate compound is not detected (ATR-IR) and deduced to be unlikely since acetic acid decomposes at low temperature on a Co metal surface (single crystal Co(0 0 0 1) experiments under ultra-high vacuum conditions). Acetic acid undergoes dissociative adsorption on the γ-Al2O3(1 1 0) and (1 0 0) surfaces (DFT), forming an acetate species. Acetic acid vapor, contacted with reduced Co/Pt/Al2O3catalyst at model FTS conditions (i.e. 1 bar(a)H2/CO:2/1 at 230 °C), results in predominantly atomic carbon deposition on the catalyst. Co-feeding of excess acetic acid during FTS does not enhance Co/Pt/Al2O3catalyst deactivation nor does it significantly impact methane selectivity. Therefore, carboxylic acids can cause atomic carbon formation on Co/γ-Al2O3catalyst during FTS and result in strongly adsorbed carboxylates on γ-Al2O3support, but these factors do not significantly impact catalyst deactivation.

    Original languageEnglish
    Pages (from-to)127-134
    Number of pages8
    JournalCatalysis Today
    Volume275
    DOIs
    Publication statusPublished - 1 Jan 2016

    Keywords

    • Alumina support
    • Carbon formation
    • Carboxylic acid
    • Catalyst deactivation
    • Fischer-Tropsch synthesis
    • Oxygenate

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