The application of synchrotron methods in characterizing iron and cobalt Fischer–Tropsch synthesis catalysts

Jacobs, Gary; Ma, Wanhong; Gao, Pei; Todić, Branislav; Bhatelia, Tejas; Bukur, Dragomir B.; Davis, Burtron H.

doi:10.1016/j.cattod.2013.05.011

Cited by 57 publications

(54 citation statements)

References 102 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The review includes a detailed consideration and analysis of the mechanisms and processes of sintering, oxidation, aluminate formation, and coking and carbide formation and under what operating conditions each is important. They summarize their and others' previous findings that oxidation primarily occurs on small (<2 nm) cobalt crystallites and at high partial pressures of water [362][363][364][365][366]. Further, they highlight the potentially complicated transformations between CoO and aluminates [362,364,367].…”

Section: Case Study: Cobalt Based Fischer-tropsch (Ft) Catalyst Regenmentioning

confidence: 72%

“…They summarize their and others' previous findings that oxidation primarily occurs on small (<2 nm) cobalt crystallites and at high partial pressures of water [362][363][364][365][366]. Further, they highlight the potentially complicated transformations between CoO and aluminates [362,364,367]. These complications highlight a complex mechanism that may be related to chemical-assisted sintering of Co FTS catalysts through a combination of the effect of CoO reduction during the initial activation of the catalysts and water exposure during operation.…”

Section: Case Study: Cobalt Based Fischer-tropsch (Ft) Catalyst Regenmentioning

confidence: 78%

“…These complications highlight a complex mechanism that may be related to chemical-assisted sintering of Co FTS catalysts through a combination of the effect of CoO reduction during the initial activation of the catalysts and water exposure during operation. First, CoO, present either due to incomplete reduction of the catalysts [368] or oxidation of the small (<2 nm) crystallites as suggested by Davis' group [369,370] can apparently increase the sintering rate due to mobility that allows them to aggregate into larger CoO clusters that are subsequently reduced to metallic Co, as inferred from evidence presented in a number of studies [79,362,[368][369][370][371]. Primarily, X-ray absorption near edge (XANES) analysis shows simultaneous increasing extent of reduction and increasing Co-Co coordination, due both to removal of oxygen and increases in particle size.…”

Section: Case Study: Cobalt Based Fischer-tropsch (Ft) Catalyst Regenmentioning

confidence: 95%

“…A recent review by the Davis group at the Center for Applied Energy Research at the University of Kentucky with Bukur at the University of Texas A&M in Qatar [362] focused on the results of studies using synchrotron radiation to characterize Co FT catalysts. The review includes a detailed consideration and analysis of the mechanisms and processes of sintering, oxidation, aluminate formation, and coking and carbide formation and under what operating conditions each is important.…”

Section: Case Study: Cobalt Based Fischer-tropsch (Ft) Catalyst Regenmentioning

confidence: 99%

See 3 more Smart Citations

Heterogeneous Catalyst Deactivation and Regeneration: A Review

2015

View full text Add to dashboard Cite

Deactivation of heterogeneous catalysts is a ubiquitous problem that causes loss of catalytic rate with time. This review on deactivation and regeneration of heterogeneous catalysts classifies deactivation by type (chemical, thermal, and mechanical) and by mechanism (poisoning, fouling, thermal degradation, vapor formation, vapor-solid and solid-solid reactions, and attrition/crushing). The key features and considerations for each of these deactivation types is reviewed in detail with reference to the latest literature reports in these areas. Two case studies on the deactivation mechanisms of catalysts used for cobalt Fischer-Tropsch and selective catalytic reduction are considered to provide additional depth in the topics of sintering, coking, poisoning, and fouling. Regeneration considerations and options are also briefly discussed for each deactivation mechanism.

show abstract

Section: Case Study: Cobalt Based Fischer-tropsch (Ft) Catalyst Regenmentioning

confidence: 72%

Section: Case Study: Cobalt Based Fischer-tropsch (Ft) Catalyst Regenmentioning

confidence: 78%

Section: Case Study: Cobalt Based Fischer-tropsch (Ft) Catalyst Regenmentioning

confidence: 95%

Section: Case Study: Cobalt Based Fischer-tropsch (Ft) Catalyst Regenmentioning

confidence: 99%

See 2 more Smart Citations

Heterogeneous Catalyst Deactivation and Regeneration: A Review

2015

View full text Add to dashboard Cite

show abstract

“…On one hand, strong interaction between the metallic phase and the support has been observed to improve catalytic activity [17], but on the other hand, it may be detrimental due to the formation of irreducible metal-support compounds such as cobalt aluminate or cobalt silicate by way of incorporating CoO into the Al 2 O 3 or SiO 2 support respectively [18], thereby leading to catalyst deactivation. In addition, carburization of the Co catalyst may lead to deactivation since the cobalt carbide (Co 2 C) formed is not a catalytically active material for FTS [4], though it has been observed to enhance the activity of the Fe-based catalyst [19].…”

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

View full text Add to dashboard Cite

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.

show abstract

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

et al. 2018

View full text Add to dashboard Cite

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.

show abstract

The application of synchrotron methods in characterizing iron and cobalt Fischer–Tropsch synthesis catalysts

Cited by 57 publications

References 102 publications

Heterogeneous Catalyst Deactivation and Regeneration: A Review

Heterogeneous Catalyst Deactivation and Regeneration: A Review

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

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

Contact Info

Product

Resources

About