Molecular structure and localization of carbon species in alumina supported cobalt Fischer–Tropsch catalysts in a slurry reactor

Peña, Diego; Griboval-Constant, Anne; Lancelot, Christine; Quijada, Melesio; Visez, Nicolas; Stéphan, Odile; Lecocq, Vincent; Diehl, Fabrice; Khodakov, Andreï Y.

doi:10.1016/j.cattod.2013.10.005

Cited by 31 publications

(31 citation statements)

References 43 publications

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“…[53] This can indicateaprobably transformation of formate speciest om ethanol [94] or to carboxylate species at higher temperatures. PeÇa et al [76] and Kistamurthy et al [97] have observed the presenceo fr esistant carboxylic acids strongly adsorbed on the alumina surface on used Co/Al 2 O 3 FTS catalysts. They suggested that the "fast formates"c ould be intermediates in the formation of methanol, while the "slow formates" remaina dsorbed on the support.…”

Section: Ex Situ Tem Characterisation:fresh and Used Catalystmentioning

confidence: 99%

“…In summary,l ow Cu loading (15/0.6 catalyst) enhancedC 5 + selectivity while high Cu loading (15/2 and 15/5 catalysts) increased CO conversion and WGS activity under the conditions studied. [70][71][72][73][74][75] It has been reported [76,77] that an increasei nO /P ratio could be relatedt oh igher degree of carbon deposition, because a-olefins may be transformed into more complexc arbon species that can be accumulatedo nt he catalysts urface. C 3 hydrocarbonss howedt he maximum O/Pw hile C 2 hydrocarbons showed the minimum O/P for all temperatures.D el a PeÇa et al [70] reported as imilart endency in agreement with our results.…”

Section: Fischer-tropsch Synthesis In Af Ixed-bed Reactormentioning

confidence: 99%

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The Effect of Copper Loading on Iron Carbide Formation and Surface Species in Iron‐Based Fischer–Tropsch Synthesis Catalysts

et al. 2018

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The effect of copper as promoter on iron carbide formation and the nature of surface species on iron‐based catalyst during Fischer–Tropsch synthesis (FTS) was investigated. Iron‐based catalysts (15 wt % of Fe) supported on alumina promoted with copper (0, 0.6, 2, and 5 wt %) were characterised in situ at relevant FTS conditions. The catalysts promoted with 2 and 5 wt % of Cu showed higher catalytic activity due to the formation of Hägg carbide (Fe5C2) detected by in situ XANES and XRD. The carbide formation is attributed to a weakening of the iron–alumina mixed‐compound interactions, and hence increasing iron reducibility and dispersion. The in situ XANES measurements indicated a maximum carburization degree (ca. 20–22 %) even at high Cu loading. The catalyst promoted with 5 wt % of Cu exhibited higher water‐gas shift activity. Aliphatic hydrocarbons, formate, and carboxylate species were detected on the catalyst surface during FTS. After exposing the spent catalysts to hydrogenation conditions, the carboxylate species remained strongly adsorbed while aliphatic hydrocarbons and formate species disappeared. The accumulation of oxygenates species on the catalyst surface increased with Cu loading. The interaction of oxygenates with alumina and iron oxide particles (FexOy) were revealed, with the latter being a possible reason for inhibition of further iron carburization.

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Section: Ex Situ Tem Characterisation:fresh and Used Catalystmentioning

confidence: 99%

Section: Fischer-tropsch Synthesis In Af Ixed-bed Reactormentioning

confidence: 99%

The Effect of Copper Loading on Iron Carbide Formation and Surface Species in Iron‐Based Fischer–Tropsch Synthesis Catalysts

et al. 2018

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“…The nucleation of carbon deposits combined with growth along catalyst support particles was recently reported for Co/Al 2 O 3 FTS catalysts. 64 Second, it is possible that not the surface oxide, but surface carbide is the mobile species. The likely formation of surface carbide species in relation with coke formation has been investigated experimentally 50 as well as theoretically.…”

Section: View Article Onlinementioning

confidence: 99%

Active phase distribution changes within a catalyst particle during Fischer–Tropsch synthesis as revealed by multi-scale microscopy

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et al. 2016

Catal. Sci. Technol.

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“…The latter method is, to the best of our knowledge, the first demonstrated application of this derivatisation method for the analysis and quantification of individual carboxylic acids in FT hydrocarbon product streams. GC-MS analysis, without the derivatisation step, has been reported for the identification of strongly adsorbed carboxylic acids present on a used Co/Al 2 O 3 catalyst after FT operation (Peña et al 2014). In that study, the used catalyst was first cleaned of paraffinic wax by a Soxhlet procedure and then the carboxylic acids, and other strongly adsorbed species, were extracted into a CH 2 Cl 2 :CH 3 OH solvent mixture for subsequent identification.…”

Section: Introductionmentioning

confidence: 99%

Quantitative carbon distribution analysis of hydrocarbons, alcohols and carboxylic acids in a Fischer-Tropsch product from a Co/TiO2 catalyst during gas phase pilot plant operation

et al. 2020

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Comprehensive two-dimensional gas chromatography (GCxGC) analysis for 1-alcohols and gas chromatography–mass spectrometry (GC-MS) analysis for carboxylic acids, derivatised as their methyl esters, have been applied to liquid and wax Fischer-Tropsch (FT) hydrocarbon products. These methods in combination with conventional one-dimensional gas chromatography (GC) analysis of the aqueous, gaseous, liquid hydrocarbon and wax products plus conventional high-performance liquid chromatography (HPLC) analysis of the aqueous phase has allowed a quantitative distribution analysis of FT hydrocarbon and oxygenated products to be demonstrated for a Co/TiO2 catalyst operating in a fixed bed gas phase pilot plant utilising CANSTM catalyst carrier devices. The GC-MS method used is, to the best of our knowledge, the first application of this derivatisation route for the quantification of individual carboxylic acids in FT hydrocarbon product streams. Whilst the hydrocarbons and oxygenates that were identified are known compounds formed during the low temperature, Co catalysed, FT process the combination of the multiple analysis techniques used has allowed a level of detail to be gained on the product composition that is seldom reported. Additionally, 1H nuclear magnetic resonance spectroscopy (NMR) and 13C NMR analyses were used to quantify the average concentration of 1-olefin, cis- and trans-2-olefins, 1-alcohol and aldehyde as appropriate for the technique used. Comparison of GCxGC versus 1H NMR and GC-MS versus a KOH titration confirmed the applicability of the chromatographic methods for the quantitative analysis of FT oxygenated compounds. Long-chain 1-alcohols and carboxylic acids, ≥ C3, were found to be present at levels of 1/10th and 1/1000th that of hydrocarbons of equivalent carbon chain length respectively. The 1-olefin:n-paraffin ratio in the hydrocarbon liquid and wax products was found to decrease significantly with increasing carbon chain length and much more so than those of the 2-olefin or 1-alcohol.

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Molecular structure and localization of carbon species in alumina supported cobalt Fischer–Tropsch catalysts in a slurry reactor

Cited by 31 publications

References 43 publications

The Effect of Copper Loading on Iron Carbide Formation and Surface Species in Iron‐Based Fischer–Tropsch Synthesis Catalysts

The Effect of Copper Loading on Iron Carbide Formation and Surface Species in Iron‐Based Fischer–Tropsch Synthesis Catalysts

Active phase distribution changes within a catalyst particle during Fischer–Tropsch synthesis as revealed by multi-scale microscopy

Quantitative carbon distribution analysis of hydrocarbons, alcohols and carboxylic acids in a Fischer-Tropsch product from a Co/TiO2 catalyst during gas phase pilot plant operation

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