Structural evolution, stability, deactivation and regeneration of Fischer-Tropsch cobalt-based catalysts supported on carbon nanotubes

Chernyak, S. A.; Burtsev, Alexander; Максимов, С. В.; Kupreenko, S. Yu.; Maslakov, K. I.; Savilov, S. V.

doi:10.1016/j.apcata.2020.117741

Cited by 24 publications

(5 citation statements)

References 76 publications

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“…These catalysts demonstrated a high FTY and selectivity to C 5+ hydrocarbons in FTS owing to the high dispersion and reducibility of iron species (Chen et al, 2015). However, problems like poor stability, high price, catalyst agglomeration, and sintering caused by the weak metal-support interaction still remain and limit the use of carbon supports on an industrial scale (Chernyak et al, 2020;Lin et al, 2017;Cheng et al, 2016). Hence, exploring new carbon materials with adjustable metal-support interaction and low price to achieve maximum iron utilization efficiency and attractive FTS performance is of prime importance.…”

Section: Introductionmentioning

confidence: 99%

Biosugarcane-based carbon support for high-performance iron-based Fischer-Tropsch synthesis

Bai

Qin

et al. 2021

iScience

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Exploiting new carbon supports with adjustable metal-support interaction and low price is of prime importance to realize the maximum active iron efficiency and industrial-scale application of Fe-based catalysts for Fischer-Tropsch synthesis (FTS). Herein, a simple, tunable, and scalable biochar support derived from the sugarcane bagasse was successfully prepared and was first used for FTS. The metal-support interaction was precisely controlled by functional groups of biosugarcane-based carbon material and different iron species sizes. All catalysts synthesized displayed high activities, and the iron-time-yield of Fe 4 /C bio even reached 1,198.9 mmol g Fe À1 s À1 . This performance was due to the unique structure and characteristics of the biosugarcane-based carbon support, which possessed abundant CÀO, C=O (h 1 (O) and h 2 (C, O)) functional groups, thus endowing the moderate metal-support interaction, high dispersion of active iron species, more active ε-Fe 2 C phase, and, most importantly, a high proportion of Fe x C/Fe surf , facilitating the maximum iron efficiency and intrinsic activity of the catalyst.

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Section: Introductionmentioning

confidence: 99%

Biosugarcane-based carbon support for high-performance iron-based Fischer-Tropsch synthesis

Bai

Qin

et al. 2021

iScience

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“…Видно, что средний размер кластеров кобальта в катализаторе до и после СФТ увеличился в несколько раз. Данный процесс может протекать при высоких температурах, в частности, при обработках в потоке водорода, а также в процессе «стабилизации» размеров кластеров в первые 100 ч. СФТ при разработке катализатора [7,[18][19][20].…”

Section: ресурсные испытанияunclassified

Deactivation Behaviour of Bifunctional Cobalt Fisher–tropsch Catalyst in Long-Run Test

2022

Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.

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In this work, several ways to decrease the deactivation degree were proposed. To prevent local overheating, exfoliated graphite was used as a heat-conductive additive in catalyst composition. To decrease the deposition of heavy waxes, H-Beta zeolite was used for secondary reactions intensification and decreasing hydrocarbons chain length in the product. In this work, pelletized zeolite-containing cobalt catalyst with exfoliated graphite as a heat-conductive additive was investigated. The test run was 2200 h long and included continuous synthesis in a 6-meter high pilot reactor. The deactivation degree after 2200 h of the test run was 13%. The investigation of catalyst samples after synthesis by means of scanning electron microscopy showed that heavy hydrocarbons did not block the pore structure of catalytic pellets. Deactivation of cobalt catalyst was decelerated seriously due to zeolite-induced decrease in molecular weight of formed hydrocarbons. Investigation of catalysts before and after the test by means of transmission electron microscopy and X-ray diffraction analysis showed an increase in the size of clusters by 3–5 times, which is another important cause for catalyst deactivation. As a result, it was found that investigated cobalt catalyst for Fisher–Tropsch synthesis has a low deactivation rate. Its implementation in the industry can help gaining better economic performance for the synthetic fuel production process.

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“…In FTS, the catalyst stability is impacted by several factors such as metal sintering (coalescence and Ostwald ripening), cobalt oxidation, and carbon deposition, which negatively affect the rate [88,89], or carbide formation, CO reduction, and restructuring of the surface, which have a positive influence [90]. In the case of Co/CNT catalysts, cobalt re-oxidation, cobalt-support interactions, wax accumulation and sintering have been identified as the main sources of catalyst deactivation [31,91,92]. In our study, the catalyst stability is expressed as the average deactivation parameter (r i /r 54h ).…”

Section: Structure/performance Relationshipsmentioning

confidence: 99%

Beyond confinement effects in Fischer-Tropsch Co/CNT catalysts

Ghogia

Machado

Cayez

et al. 2021

Journal of Catalysis

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Fischer-Tropsch catalyst preparation parameters, such as cobalt precursor and impregnation solvent, determine structure and in fine catalytic performances of Co-based catalysts. Co particles of 3-7 nm mean size were prepared by incipient wetness impregnation on surface-oxidized CNT. In this work the crucial impact of the chemistry operating between the Co precursor and the support during catalyst preparation on the catalyst properties is demonstrated and the influence of CNT surface chemistry on catalyst characteristics has been assessed. Very good correlations were found between: i) the reduction degree of the catalysts and the concentration of the Co(OOC-) surface species; ii) the Co hcp /Co fcc ratio and the amount of CO-releasing groups on the support surface; iii) the extent of hydrogen spillover and the concentration of quinone surface groups. The initial catalytic activity could only be correlated to a combination of catalyst features: percentage of Co hcp , Co confinement, hydrogen spillover, and surprisingly the inverse of the Co initial particle size. No significant differences in S C5+ selectivity were observed, in accordance with comparable final Co particle size. Finally, the stability of the catalyst can be correlated with the initial Co particle size and the percentage of Co hcp in the catalyst. These results confirm the significant impact of the precursor/support couple on the structure and performance of Co/CNT catalysts, and reveal for the first time an inverse correlation between Co particle size and activity, which is attributed to the confined Co hcp phase.

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Structural evolution, stability, deactivation and regeneration of Fischer-Tropsch cobalt-based catalysts supported on carbon nanotubes

Cited by 24 publications

References 76 publications

Biosugarcane-based carbon support for high-performance iron-based Fischer-Tropsch synthesis

Biosugarcane-based carbon support for high-performance iron-based Fischer-Tropsch synthesis

Deactivation Behaviour of Bifunctional Cobalt Fisher–tropsch Catalyst in Long-Run Test

Beyond confinement effects in Fischer-Tropsch Co/CNT catalysts

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