Studies of the Fischer--Tropsch Synthesis. V. Activities and Surface Areas of Reduced and Carburized Cobalt Catalysts

Anderson, R. B.; Hall, W. Keith; Krieg, Abraham.; Seligman, Bernard

doi:10.1021/ja01169a047

Cited by 58 publications

(30 citation statements)

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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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Section: Discussionmentioning

confidence: 99%

Acetylenes as probes in the Fischer–Tropsch Reaction

2005

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“…The second reduction region at 320-580 °C can be attributed It is known that the pore size markedly affects the reduction process of cobalt catalysts by altering the Co 3 O 4 particle size [13]. The Co 3 O 4 particle size increases with increasing catalyst pore size (Table 1).…”

Section: H 2 -Temperature Programmed Reductionmentioning

confidence: 96%

“…The high surface area favors a high degree of cobalt dispersion, while the large pore size with its narrow distribution controls the cobalt particle size, improves the diffusion of reactants and products in the mesoporous channel, and improves the distribution of hydrocarbon products from FTS [11,12]. Anderson et al [13] reported that the activity and selectivity of cobalt based catalysts in FTS could be affected by altering their pore size, and they found that the increase in methane selectivity with decreasing average pore size was due to a mass transport phenomenon. Using SBA-15, MCM-41 and commercial mesoporous silica as supports, Khodakov et al.…”

Section: Introductionmentioning

confidence: 99%

Effect of the pore size of Co/SBA-15 isomorphically substituted with zirconium on its catalytic performance in Fischer-Tropsch synthesis

Tao

Liew

2010

Sci. China Chem.

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Cobalt catalysts supported on a series of mesoporous SBA-15 materials isomorphically substituted with zirconium (Zr/Si atomic ratio = 1/20) with different pore sizes (5.7 nm, 7.8 nm, 11.6 nm, 17.6 nm) have been synthesized. The catalysts were characterized by transmission electron microscopy, 29 Si solid state magic angle spinning (MAS) NMR, N 2 adsorption-desorption measurements, X-ray powder diffraction, X-ray photoelectron spectroscopy, H 2 -temperature programmed reduction, H 2 -temperature programmed desorption and O 2 titrations. The results indicated that larger pore size led to weaker interactions between cobalt and the supports which lowered the temperature of both reduction steps (Co 3 O 4 CoO and CoO Co → → 0 ). The catalytic performances of the catalysts in Fischer-Tropsch synthesis (FTS) were tested in a fixed bed reactor. It was found that the FTS catalytic activity and product selectivity depended strongly on the pore size of the catalysts. The catalyst with a pore size of 7.8 nm showed the best FTS activity, and the catalyst with a pore size of 17.6 nm showed the highest selectivity to C 12 -C 20 and C 20+ hydrocarbons.Fischer-Tropsch synthesis, cobalt catalyst, SBA-15, pore size, zirconium, isomorphic substitution

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“…The BET results indicate that pore size of Fe 2 O 3 -PVA catalyst is much larger than that of the Fe 2 O 3 catalyst. Anderson et al 42 reported that the FTS activity and selectivity of catalyst could be affected by their pore sizes. Khodakov et al 43 suggested that lower reducibility of small particles is likely to be one of the reasons responsible for the lower Fischer-Tropsch reaction rates and higher methane selectivity on narrow pore catalysts.…”

Section: Fts Performancementioning

confidence: 99%

Effect of PVA Concentration on Structure and Performance of Precipitated Iron-Based Catalyst for Fischer-Tropsch Synthesis

Dong

Liu

et al. 2017

J. Braz. Chem. Soc.

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Fe 2 O 3 catalysts were prepared by co-precipitation method with the assistance of polyvinyl alcohol (PVA) for Fischer-Tropsch synthesis. Effects of PVA concentration on structure and performance of the catalyst were investigated in a fixed reactor at 230-310 °C, 1.5 MPa, 2000 h -1 , and syngas H 2 /CO = 2.0. The catalysts were characterized by N 2 adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), H 2 or CO temperature-programmed reduction (TPR) and H 2 temperature-programmed desorption (H 2 -TPD), Fourier transform infrared (FTIR) spectra and thermogravimetric analysis (TGA). It was found that there was strong interaction between Fe and PVA, which controlled the structure of the catalyst. Among the catalysts investigated, the catalyst prepared with 15 wt.% PVA exhibited better catalytic performance due to the dispersion of iron oxides and the formation of the more active phase on the catalyst. Meanwhile, this catalyst showed the high selectivity to heavy hydrocarbons and satisfactory thermal stability.Keywords: Fischer-Tropsch synthesis, iron-based catalyst, PVA concentration, structure, stability IntroductionFischer-Tropsch synthesis (FTS), an efficient technology to convert syngas into liquid fuels and chemicals, has attracted great interest due to the shrinking of the petroleum resource in the past decades.1 Iron-based catalysts have attracted considerable focus, thanks to their low cost, high activity and excellent water-gas-shift reactivity, which match coal gasification with low H 2 /CO ratio. 2 Remarkably, three principal challenges are posed for iron-based FTS catalyst: activity, selectivity and stability. 3 It is well known that the activity, selectivity and stability of FTS catalysts rely strongly on the texture and surface properties of the resultant catalysts. 4 Most of all, the pore size of catalyst is one of the key factors, which has significant effect on the mass transfer of reactants and products, 5 the re-adsorption of the α-alkene, and the chemisorption ratio of H 2 on the surface active sites exposed. 6 Therefore, these factors are vital for the performance of catalyst in the FTS. For instance, smaller pore size of catalyst can afford high Brunauer, Emmett and Teller (BET) surface area and dispersion of the catalyst. However, diffusion effects of products were limited, resulting in light hydrocarbons as the main product for excessive hydrogenation. In contrast, the larger pore size of catalyst can facilitate the diffusion of products, and thus products of heavy hydrocarbons are obtained.7 Tao et al. 8 proposed that the FTS catalytic activity and product selectivity rely strongly on the pore size distribution of the catalysts. Xiong et al. 9 found that CO conversion increased and then decreased with the pore size in the range studied. Sun and co-workers 10,11 reported that the FTS catalytic performances were closely correlated to the pore sizes of the mesoporous zirconia.In general, the preparation process has a significant e...

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Studies of the Fischer--Tropsch Synthesis. V. Activities and Surface Areas of Reduced and Carburized Cobalt Catalysts

Cited by 58 publications

References 1 publication

Acetylenes as probes in the Fischer–Tropsch Reaction

Acetylenes as probes in the Fischer–Tropsch Reaction

Effect of the pore size of Co/SBA-15 isomorphically substituted with zirconium on its catalytic performance in Fischer-Tropsch synthesis

Effect of PVA Concentration on Structure and Performance of Precipitated Iron-Based Catalyst for Fischer-Tropsch Synthesis

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