Fischer–Tropsch: Product Selectivity–The Fingerprint of Synthetic Fuels

Shafer, Wilson D.; Gnanamani, Muthu Kumaran; Graham, Uschi M.; Yang, Jia; Masuku, Cornelius Mduduzi; Jacobs, Gary; Davis, Burtron H.

doi:10.3390/catal9030259

Cited by 95 publications

(71 citation statements)

References 167 publications

(287 reference statements)

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“…The higher methane selectivity result is not surprising, because nickel has a higher hydrogenation capability. Shafer et al [17] explain that the back-donation of nickel is so strong that the vinylic intermediate is not suitably stabilized, precluding the chain growth. Higher methane selectivity was also reported in previous studies where different Ni/Co ratios were investigated [39,40], although recent results suggest that lower amounts (e.g., <25% [41]) of Ni favor a selectivity closer to that of pure cobalt.…”

Section: Discussionmentioning

confidence: 99%

“…Cobalt is a d 7 metal and has an electronic configuration suitable for growing long-chained hydrocarbons. The metal has the right balance in that it is able to dissociate CO, as well as stabilize the vinylic intermediate in the appropriate sp 3 configuration, such that chain growth is controlled to one side, producing primarily straight chained paraffins, 1-olefins, and 1-alcohols [17]. Nickel, however, is a d 8 metal, and the electronic back-donation capability of Ni is excessive for the FTS application, such that the vinylic intermediate is insufficiently stabilized, resulting primarily in undesired light gas production [17].…”

mentioning

confidence: 99%

“…The metal has the right balance in that it is able to dissociate CO, as well as stabilize the vinylic intermediate in the appropriate sp 3 configuration, such that chain growth is controlled to one side, producing primarily straight chained paraffins, 1-olefins, and 1-alcohols [17]. Nickel, however, is a d 8 metal, and the electronic back-donation capability of Ni is excessive for the FTS application, such that the vinylic intermediate is insufficiently stabilized, resulting primarily in undesired light gas production [17]. Thus, there are questions related to how much nickel can be added to cobalt nanoparticles such that the resulting alloy still possesses adequate hydrocarbon selectivity for FT, and whether a catalyst possessing a nickel core and a cobalt shell might be developed such that the reaction occurs primarily on a cobalt shell.Finally, there is the problem of stability with heterogenized cobalt catalysts [9,[18][19][20][21].…”

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confidence: 99%

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The Preparation and Characterization of Co–Ni Nanoparticles and the Testing of a Heterogenized Co–Ni/Alumina Catalyst for CO Hydrogenation

et al. 2019

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Samples of well-controlled nanoparticles consisting of alloys of cobalt and nickel of different atomic ratios were synthesized using wet chemical methods with oleylamine as the solvent and the reducing agent. These materials were characterized by a variety of techniques, including high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Small amounts of heterogenized catalysts were prepared using alumina as the support. However, the potential for use of Co–Ni catalysts in CO hydrogenation was explored using a larger amount of Co–Ni/alumina catalyst prepared from standard aqueous impregnation methods and tested in a continuously stirred tank reactor (CSTR) for Fischer–Tropsch synthesis (FTS). Results are compared to a reference catalyst containing only cobalt. The heterogenized catalysts were characterized using synchrotron methods, including temperature programmed reduction with extended X-ray absorption fine structure spectroscopy and X-ray absorption near edge spectroscopy (TPR-EXAFS/XANES). The characterization results support intimate contact between Co and Ni, strongly suggesting alloy formation. In FTS testing, drawbacks of Ni addition included decreased CO conversion on a per gram catalyst basis, although Ni did not significantly impact the turnover number of cobalt, and produced slightly higher light gas selectivity. Benefits of Ni addition included an inverted induction period relative to undoped Co/Al2O3, where CO conversion increased with time on-stream in the initial period, and the stabilization of cobalt nanoparticles at a lower weight % of Co.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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The Preparation and Characterization of Co–Ni Nanoparticles and the Testing of a Heterogenized Co–Ni/Alumina Catalyst for CO Hydrogenation

et al. 2019

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“…Cobalt-supported catalysts are quite promising for many reactions of environmental and industrial interest such as volatile organic compounds oxidation [1], CO 2 hydrogenation [2], the Fischer-Tropsch process [3,4], and electrocatalysis [5].…”

Section: Introductionmentioning

confidence: 99%

The Influence of Preparation Method on the Physicochemical Characteristics and Catalytic Activity of Co/TiO2 Catalysts

Vakros

2020

Catalysts

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Two Co/TiO2 catalysts with 7% CoO/g loading were prepared using equilibrium deposition filtration and the dry impregnation method. The two catalysts were characterized with various physicochemical techniques and tested for the degradation of sulfamethaxazole (SMX) using sodium persulfate (SPS) as the oxidant. It was found that the two catalysts exhibit different physicochemical characteristics. The equilibrium deposition filtration (EDF) catalyst had a higher dispersion of cobalt phase, more easily reduced Co(III) species, and a higher ratio of Co(III)/Co(II) species. The interactions between Co-deposited species and the titania surface were monitored with diffuse reflectance spectroscopy in all the preparation steps, and it was found that they increased during drying and calcination, while EDF favored the formation of surface species with strong interactions with the support. Finally, the EDF catalyst was more active for the degradation of sulfamethaxazole due to its better physicochemical characteristics.

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“…Several metals are active in FT reaction, such as nickel (Ni), ruthenium (Ru), cobalt (Co), and iron (Fe). Shafer et al [11] recently tested different types of catalysts in a continuously stirred tank reactor, showing how each metal-based catalyst results in dissimilar product selectivity. They found out that Co and Ru catalysts were more selective towards n-paraffins and α-olefins, while the Fe catalyst would be responsible for the synthesis of a higher amount of branched isomers.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Study Based on the Carbide Mechanism of a Co-Pt/γ-Al2O3 Fischer–Tropsch Catalyst Tested in a Laboratory-Scale Tubular Reactor

et al. 2019

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A Co-Pt/γ-Al2O3 catalyst was manufactured and tested for Fischer–Tropsch applications. Catalyst kinetic experiments were performed using a tubular fixed-bed reactor system. The operative conditions were varied between 478 and 503 K, 15 and 30 bar, H2/CO molar ratio 1.06 and 2.11 at a carbon monoxide conversion level of about 10%. Several kinetic models were derived, and a carbide mechanism model was chosen, taking into account an increasing value of termination energy for α-olefins with increasing carbon numbers. In order to assess catalyst suitability for the determination of reaction kinetics and comparability to similar Fischer–Tropsch Synthesis (FTS) applications, the catalyst was characterized with gas sorption analysis, temperature-programmed reduction (TPR), and X-ray diffraction (XRD) techniques. The kinetic model developed is capable of describing the intrinsic behavior of the catalyst correctly. It accounts for the main deviations from the typical Anderson-Schulz-Flory distribution for Fischer–Tropsch products, with calculated activation energies and adsorption enthalpies in line with values available from the literature. The model suitably predicts the formation rates of methane and ethylene, as well as of the other α-olefins. Furthermore, it properly estimates high molecular weight n-paraffin formation up to carbon number C80.

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Fischer–Tropsch: Product Selectivity–The Fingerprint of Synthetic Fuels

Cited by 95 publications

References 167 publications

The Preparation and Characterization of Co–Ni Nanoparticles and the Testing of a Heterogenized Co–Ni/Alumina Catalyst for CO Hydrogenation

The Preparation and Characterization of Co–Ni Nanoparticles and the Testing of a Heterogenized Co–Ni/Alumina Catalyst for CO Hydrogenation

The Influence of Preparation Method on the Physicochemical Characteristics and Catalytic Activity of Co/TiO2 Catalysts

Kinetic Study Based on the Carbide Mechanism of a Co-Pt/γ-Al2O3 Fischer–Tropsch Catalyst Tested in a Laboratory-Scale Tubular Reactor

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