The effect of synthesis gas composition on the Fischer–Tropsch synthesis over Co/γ-Al2O3 and Co–Re/γ-Al2O3 catalysts

Tristantini, Dewi; Lögdberg, Sara; Gevert, Börje Sten; Borg, Øyvind; Holmén, Anders

doi:10.1016/j.fuproc.2007.01.012

Cited by 91 publications

(40 citation statements)

References 26 publications

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“…One would expect the S C5? to decrease with increased WGS activity as the H 2 /CO ratio in the reactor is higher [27] and the water partial pressure is lower [20]. These findings are, however, in agreement with those of Chanenchuk et al [9] who reported similar selectivities for a pure Co-catalyst as for a 67WGS-33FT mixture.…”

Section: Activity Resultssupporting

confidence: 86%

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Investigation of Mixtures of a Co-Based Catalyst and a Cu-Based Catalyst for the Fischer–Tropsch Synthesis with Bio-Syngas: The Importance of Indigenous Water

et al. 2011

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A series of different mechanical mixtures of a narrow-pore Co/c-Al 2 O 3 catalyst and a Cu-based WGScatalyst has been investigated in the low-temperature Fischer-Tropsch synthesis (483 K, 20 bar) with a model bio-syngas (H 2 /CO = 1.0) in a fixed-bed reactor. The higher the fraction of WGS-catalyst in the mixture, the lower is the Co-catalyst-time yield to hydrocarbons. This is ascribed to a strong positive kinetic effect of water on the Fischer-Tropsch rate of the Co-catalyst, showing the importance of the indigenously produced water, especially in fixed-bed reactors where the partial pressure of water is zero at the reactor inlet. A preliminary kinetic modeling suggests that the reaction order in P H 2 O is 0.3 for the Co/ c-Al 2 O 3 catalyst in the range of the studied reactor-average partial pressures of water (i.e., 0.04-1.2 bar).

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Section: Activity Resultssupporting

confidence: 86%

“…[20,25]. The average particle size of Co 0 , assuming spherical shape, was estimated according to [26][27][28]:…”

Section: Catalyst Characterization Methodsmentioning

confidence: 99%

Investigation of Mixtures of a Co-Based Catalyst and a Cu-Based Catalyst for the Fischer–Tropsch Synthesis with Bio-Syngas: The Importance of Indigenous Water

et al. 2011

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“…Another approach that has been applied in FTS to improve selectivity towards the C 5+ products is through CO-enriched syngas feeds, which lowers CH 4 formation [10]. Nevertheless, where gas composition has been used to determine the product spectrum, low CO conversions have prevailed, with an increased reaction rate being observed at higher H 2 :CO ratios above 1.6, and this has an added advantage of using less catalyst quantities for the same feed conversion [2].…”

Section: Introductionmentioning

confidence: 99%

Effect of CO Concentration on the α-Value of Plasma-Synthesized Co/C Catalyst in Fischer-Tropsch Synthesis

Aluha

Abatzoglou

2017

Catalysts

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Abstract:A plasma-synthesized cobalt catalyst supported on carbon (Co/C) was tested for Fischer-Tropsch synthesis (FTS) in a 3-phase continuously-stirred tank slurry reactor (3-φ-CSTSR) operated isothermally at 220 • C (493 K), and 2 MPa pressure. Initial syngas feed stream of H 2 :CO ratio = 2 with molar composition of 0.6 L/L (60 vol %) H 2 and 0.3 L/L (30 vol %) CO, balanced in 0.1 L/L (10 vol %) Ar was used, flowing at hourly space velocity (GHSV) of 3600 cm 3 ·h −1 ·g −1 of catalyst. Similarly, other syngas feed compositions of H 2 :CO ratio = 1.5 and 1.0 were used. Results showed~40% CO conversion with early catalyst selectivity inclined towards formation of gasoline (C 4 -C 12 ) and diesel (C 13 -C 20 ) fractions. With prolonged time-on-stream (TOS), catalyst selectivity escalated towards the heavier molecular-weight fractions such as waxes (C 21+ ). The catalyst's α-value, which signifies the probability of the hydrocarbon-chain growth was empirically determined to be in the range of 0.85-0.87 (at H 2 :CO ratio = 2), demonstrating prevalence of the hydrocarbon-chain propagation, with particular predisposition for wax production. The inhibiting CO effect towards FTS was noted at molar H 2 :CO ratio of 1.0 and 1.5, giving only~10% and~20% CO conversion respectively, although with a high α-value of 0.93 in both cases, which showed predominant production of the heavier molecular weight fractions.

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“…The chemisorption measurements were conducted on a Micromeritics ASAP 2020C unit at 308 K, after reducing about 0.15 g of the calcined catalysts in flowing hydrogen at 623 K (heating rate: 1 K/min) for 16 h. The average particle size of Co 0 , assuming spherical shape, was estimated according to [7][8][9]:…”

Section: Catalyst Characterization Methodsmentioning

confidence: 99%

Evidence for Diffusion-Controlled Hydrocarbon Selectivities in the Fischer–Tropsch Synthesis Over Cobalt Supported on Ordered Mesoporous Silica

et al. 2011

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A series of four cobalt-based catalysts (two of which promoted with ruthenium) supported on SiO 2 or SBA-15 were prepared and tested in the Fischer-Tropsch synthesis at industrially relevant process conditions (483 K, 20 bar, H 2 /CO ratio = 2.1, pellet size: 53-90 lm). The catalysts were characterized by N 2 -adsorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR), H 2 -chemisorption and transmission electron microscopy (TEM). Ru as promoter enhanced the activity but not the selectivity to long-chain hydrocarbons (S C 5þ ). The S C 5þ values of the SBA-supported catalysts were very low, especially at low conversion levels (i.e. low water partial pressure), suggesting that CO diffusion limitation increased the H 2 /CO ratio inside the 1-dimensional (1-D) porous network. A superimposition of the selectivity results on the correlations found in our recent study, derived for Co-based catalysts supported on c-Al 2 O 3 , a-Al 2 O 3 and TiO 2 free from diffusion limitations, was made. While the SiO 2 -supported catalysts with a 3-D porous structure followed the correlations, the SBA-catalysts deviated significantly at low conversions, giving a further indication that the selectivity results of these catalysts were affected by CO diffusion limitations. Hence, it may be concluded that the kinetically significant diffusion distances (i.e. those long enough to cause an intrapore H 2 / CO ratio higher than that of the bulk gas phase) are probably much shorter for 1-D porous networks than for conventional 3-D supports. This is explained by a significantly lower effective diffusivity in 1-D porous networks. The potential of using the correlations between non-ASF distributed hydrocarbons and C 5? , to give insight on the occurrence of diffusion limitations, was confirmed by superimposing data from the literature that were anticipated to be influenced by CO diffusion limitations.

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The effect of synthesis gas composition on the Fischer–Tropsch synthesis over Co/γ-Al2O3 and Co–Re/γ-Al2O3 catalysts

Cited by 91 publications

References 26 publications

Investigation of Mixtures of a Co-Based Catalyst and a Cu-Based Catalyst for the Fischer–Tropsch Synthesis with Bio-Syngas: The Importance of Indigenous Water

Investigation of Mixtures of a Co-Based Catalyst and a Cu-Based Catalyst for the Fischer–Tropsch Synthesis with Bio-Syngas: The Importance of Indigenous Water

Effect of CO Concentration on the α-Value of Plasma-Synthesized Co/C Catalyst in Fischer-Tropsch Synthesis

Evidence for Diffusion-Controlled Hydrocarbon Selectivities in the Fischer–Tropsch Synthesis Over Cobalt Supported on Ordered Mesoporous Silica

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