The Role of Bulk Cobalt Carbide in the Fischer—Tropsch Synthesis<sup>1</sup>

Weller, Sol W.; Hofer, L. J. E.; Anderson, R. B.

doi:10.1021/ja01182a108

Cited by 92 publications

(63 citation statements)

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“…A short catalytic test carried out just after a treatment under CO (formation of the carbide phase) confirmed, in agreement with the literature [24,25], that the carbide is not highly active in Fischer-Tropsch synthesis.…”

Section: Effect Of Structure On Fischer-tropsch Activitysupporting

confidence: 90%

Microstructure of Supported Cobalt Fischer-Tropsch Catalysts

Ducreux

Rebours

Lynch

et al. 2008

Oil & Gas Science and Technology - Rev. IFP

142

130

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Résumé -Microstructure de catalyseurs Fischer-Tropsch à base de cobalt supporté -La structure de particules métalliques de cobalt supporté sur silice ou sur alumine, et en présence ou non d'un promoteur (Ru), a été étudiée in situ par diffraction des rayons X conventionnelle et anomale. Par comparaison avec des diagrammes simulés, il est montré que cette structure est caractérisée par la présence de défauts d'empilement dont la densité est directement reliée à la température de réduction du cobalt. Des traitements de carburation/décarburation sous CO et H 2 nous ont permis de modifier de manière contrôlée la microstructure du cobalt métallique pour un même support tout en limitant la variation de la taille des particules. Quel que soit le support, et en présence ou non d'un promoteur, les basses températures de réduction favorisent la formation de la forme hexagonale compacte du cobalt, alors qu'une réduction à haute température favorisera la forme cubique faces centrées. Dans les conditions de la synthèse Fischer-Tropsch, les catalyseurs contenant du cobalt à forte densité d'empilements de type hexagonal compact montrent une activité en conversion du CO nettement supérieure à celle des catalyseurs majoritairement cubiques. Abstract -Microstructure of Supported Cobalt Fischer-Tropsch Catalysts -The structures of metallic cobalt particles supported on silica (with and without Ru promoter) and on alumina have been investigated in-situ by conventional and anomalous X-ray diffraction.Comparison with simulated XRD patterns shows the structure to consist of a defect phase characterised by the presence of stacking faults, the density of which is directly related to the temperature at which the cobalt oxide is reduced.

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Section: Effect Of Structure On Fischer-tropsch Activitysupporting

confidence: 90%

Microstructure of Supported Cobalt Fischer-Tropsch Catalysts

Ducreux

Rebours

Lynch

et al. 2008

Oil & Gas Science and Technology - Rev. IFP

142

130

View full text Add to dashboard Cite

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“…Oxidation of metallic cobalt in cobaltbased Fischer-Tropsch synthesis has been long debated in the open literature [28,60,[146][147][148][149][150][151][152]. However, it has been shown [28,151,152] that oxidation of the catalyst with water should not occur under realistic Fischer-Tropsch conditions if the metallic cobalt crystallites are larger than 4-5 nm (it should be pointed out here that even larger crystallites are required in the reduced catalyst to obtain the highest intrinsic activitysee Fig.…”

Section: Inherent Catalyst Deactivation In the Fischertropsch Synthesismentioning

confidence: 99%

Fischer‐Tropsch Catalysts for the Biomass‐to‐Liquid (BTL)‐Process

2008

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The Fischer-Tropsch synthesis is at the heart of the Biomass-to-Liquids (BTL) process. Feasibility studies published in open literature typically consider cobaltbased catalysts for the Fischer-Tropsch synthesis. Here, we present an overview on the history and development up until the present for both cobalt-and ironbased Fischer-Tropsch catalysts. The role of the support material and various other additives to the catalyst formulation are discussed in detail with regard to activity, catalyst deactivation, and selectivity. Tentative explanations for e.g. the observed size dependency in cobalt-based catalysts and phase transformations in iron-based Fischer-Tropsch catalysts are offered. The productivity of cobalt-based catalysts at high conversion level is currently higher than that of iron-based catalysts. Nevertheless, it is argued that iron-based catalysts may be an attractive option for the BTL-process, since it is much cheaper, impacting on the cost of the process due to inevitable process set-ups in industrial operation. Improvement of current iron-based catalysts is however desired.

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“…This mechanism is generally accepted for cobalt-catalyzed FT reactions although there was some objection since there is no known cobalt carbide. It was then realized that no cobalt carbide phase is involved; only surface-bonded carbon is assumed [43][44][45].…”

Section: Discussionmentioning

confidence: 99%

Acetylenes as probes in the Fischer–Tropsch Reaction

2005

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Long-chain acetylenic molecules (from C6 to C10) have been added as probe molecules to the synthesis gas feed in FischerTropsch(FT) reactions on Co/Al 2 O 3 at 0.7 Mpa and 150-220°C. The acetylenic molecules initiated the reaction at temperatures as low as 150°C. Use of a phenyl-substituted acetylene allowed the FT products initiated by the alkyne to be distinguished from base case FT synthesis. Terminal alkynes produced straight chain products while internal alkynes produced both terminal and internal products. Aldehydes and alcohols with one carbon more than the added acetylenic probe molecule were the only oxygenates formed, perhaps by a hydroformylation type of reaction.

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The Role of Bulk Cobalt Carbide in the Fischer—Tropsch Synthesis¹

Cited by 92 publications

References 0 publications

Microstructure of Supported Cobalt Fischer-Tropsch Catalysts

Microstructure of Supported Cobalt Fischer-Tropsch Catalysts

Fischer‐Tropsch Catalysts for the Biomass‐to‐Liquid (BTL)‐Process

Acetylenes as probes in the Fischer–Tropsch Reaction

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The Role of Bulk Cobalt Carbide in the Fischer—Tropsch Synthesis1

Cited by 92 publications

References 0 publications

Microstructure of Supported Cobalt Fischer-Tropsch Catalysts

Microstructure of Supported Cobalt Fischer-Tropsch Catalysts

Fischer‐Tropsch Catalysts for the Biomass‐to‐Liquid (BTL)‐Process

Acetylenes as probes in the Fischer–Tropsch Reaction

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The Role of Bulk Cobalt Carbide in the Fischer—Tropsch Synthesis¹