The role of carboxylic acid in cobalt Fischer-Tropsch synthesis catalyst deactivation
| Autor: | H. Preston, IM Ionel Ciobica, A.M. Saib, J.W. Niemantsverdriet, D. Kistamurthy, C.J. Weststrate, W. Janse van Rensburg, D.J. Moodley |
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| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
inorganic chemicals
Alumina support Catalyst deactivation Catalyst support Carboxylic acid Inorganic chemistry chemistry.chemical_element 02 engineering and technology 010402 general chemistry 01 natural sciences Catalyst poisoning Catalysis Acetic acid chemistry.chemical_compound Oxygenate chemistry.chemical_classification Carbon formation Fischer–Tropsch process General Chemistry Fischer-Tropsch synthesis 021001 nanoscience & nanotechnology 0104 chemical sciences chemistry 0210 nano-technology Cobalt Carbon |
| Zdroj: | Catalysis Today, 275, 127-134. Elsevier |
| ISSN: | 0920-5861 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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