Raising Co/Al2O3 catalyst lifetime in Fischer–Tropsch synthesis by using a novel dual-bed reactor

Tavasoli, Ahmad; Nakhaeipour, Ali; Sadaghiani, Kambiz

doi:10.1016/j.fuproc.2006.12.002

Cited by 21 publications

(14 citation statements)

References 12 publications

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“…• C (Tavasoli et al, 2005(Tavasoli et al, , 2007b. XRD results also reveal that, morphology change and as well as the rate of catalyst deactivation in the last catalytic beds are much higher than that of the earlier beds and the catalyst deactivation of the earlier beds (i.e.1 and 2) is mostly reversible but the catalyst deactivation of the last two beds (3 and mainly 4) is not completely reversible.…”

Section: Structural Changes Of the Catalystsmentioning

confidence: 90%

“…• C. Small tailing of the second TPR peak also reveals that in ruthenium promoted cobalt catalyst the degree of interaction between active metal and support is not significant (Tavasoli et al, 2005(Tavasoli et al, , 2007b. Figure 8 shows the TPR spectra of the used catalysts of all beds.…”

Section: Structural Changes Of the Catalystsmentioning

confidence: 97%

“…This reveals that during first 200 h FT synthesis the deactivation rate is not related to the number of the catalyst active sites and the deactivation is caused by exterior factors such as partial pressure of water. It has been suggested that in FT synthesis on alumina-supported cobalt catalysts at high conversions, the loss of active sites is caused by water-induced oxidation of cobalt and formation of more refractory forms of oxidized cobalt generated by cobalt-alumina interactions (Krishnamurthy et al, 2002;Das et al, 2003;Kiss et al, 2003;Jacobs et al, 2004;Tavasoli et al, 2005Tavasoli et al, , 2007b. When time on stream exceeded 200 h the catalyst deactivation could be simulated with a power law expression: Assuming the deactivation rate is:…”

Section: Activity and Selectivity Studiesmentioning

confidence: 99%

“…When cobalt is deactivated, it means it is converted into either CoO or Co 3 O 4 or mixed oxides of the form xCoO·yAl 2 O 3 or CoAl 2 O 4 . This is not thermodynamically possible unless this is affected by water (Jongsomjit and Goodwin, 2002;Tavasoli et al, 2007b).…”

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confidence: 99%

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Morphology and deactivation behaviour of Co–Ru/γ‐Al₂O₃ Fischer–Tropsch synthesis catalyst

Tavasoli

Irani²,

Abbaslou

et al. 2008

Can J Chem Eng

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Deactivation of Co-Ru/ -Al 2 O 3 Fischer-Tropsch (FT) synthesis catalyst along the catalytic bed over 850 h of time-on-stream (TOS) was investigated. Catalytic bed was divided into four parts and structural changes of the spent catalysts collected from each catalytic bed after FT synthesis were studied using BET, ICP, XRD, TPR, carbon determination, H 2 chemisorption and oxygen titration techniques. Rapid deactivation was observed during first 200 h of FT synthesis. In this case, the deactivation rate was not dependent on the number of the catalyst active sites. It was zero order to CO conversion and independent of the size of active sites. Beyond the TOS of 200 h, the deactivation could be simulated with a power law expression: −dX CO /dt = kX 28.5 CO . The physical properties of the catalyst charged in 1st half of the reactor did not change significantly. Interaction of cobalt with alumina and formation of mixed oxides of the form xCoO·yAl 2 O 3 and CoAl 2 O 4 was increased along the catalytic bed. Percentage reducibility and dispersion decreased by 2.4-25.5% and 0.5-8.8% for the catalyst in the beds 1 and 4, respectively. Particle diameter increased by 0.8-6.1% for the catalyst in the beds 1 and 4 respectively suggesting higher rate of sintering at last catalytic bed. The amount of coke formation in the 4th catalytic bed was 6 times more than that of in bed 1.On aétudié la désactivation d'un catalyseur de synthèse Fischer-Tropsch (FT) au Co-Ru/ -Al 2 O 3 dans un lit catalytique pendant 850 h de temps de fonctionnement (TOS). Le lit catalytique aété divisé en quatre parties et les changements structurels des catalyseurs consommés recueillis dans chaque lit catalytique après la synthèse FT ontétéétudiés en utilisant le BET, ICP, XRD, TPR et la détermination du carbone, la chimisorption du H 2 et les techniques de titration de l'oxygène. Une désactivation rapide aété observée lors des 200 premières heures de synthèse FT. Dans ce cas, la vitesse de désactivation ne dépend pas du nombre de sites de catalyseur actifs. La conversion de CO est d'ordre zéro et indépendante de la taille des sites actifs. Au-delà de 200 h de TOS, la désactivation a puêtre simulée avec une expression de loi de puissance, soit −dX CO /dt = kX 28,5 CO . Les propriétés physiques du catalyseur chargé dans la première moitié du réacteur n'ont pas changé significativement. L'interaction du cobalt avec l'alumine et la formation d'oxydes mixtes de la forme xCoO·yAl 2 O 3 et CoAl 2 O 4 ontété augmentées dans le lit catalytique. La dispersion et la réductibilité en pourcentage ont diminué de 2,4à 25,5% et de 0,5à 8,8% pour le catalyseur des lits 1 et 4, respectivement. Le diamètre des particules a augmenté de 0,8à 6,1% pour le catalyseur des lits 1 et 4, respectivement, ce qui suggère une vitesse de frittage plusélevée dans le dernier lit catalytique. L'importance de la formation de coke dans le 4è me lit catalytique est de 6 fois supérieure que dans le lit 1.

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Section: Structural Changes Of the Catalystsmentioning

confidence: 90%

Section: Structural Changes Of the Catalystsmentioning

confidence: 97%

Section: Activity and Selectivity Studiesmentioning

confidence: 99%

mentioning

confidence: 99%

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Morphology and deactivation behaviour of Co–Ru/γ‐Al₂O₃ Fischer–Tropsch synthesis catalyst

Tavasoli

Irani²,

Abbaslou

et al. 2008

Can J Chem Eng

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“…It has been reported that metal–support interactions may appreciably affect surface properties, and hence catalytic activities . Especially, Co nanoparticles supported on Al 2 O 3 substrates exhibit an attractive performance in oxidation reactions because of the favourable mechanical properties of the alumina support . It has been reported that metal–support interactions can significantly improve the physical properties of the surface of a catalyst and hence the catalytic activity.…”

Section: Introductionmentioning

confidence: 99%

Highly selective aerobic oxidation of alkylarenes catalyzed by cobalt‐based nanocatalyst in aqueous solution

Albadi

Alihosseinzadeh

Jalali³

et al. 2017

Applied Organom Chemis

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The catalytic aerobic oxidation of alkylarenes catalyzed by cobalt supported on a highly crystalline γ‐Al2O3 support (Co/Al2O3 nanocatalyst) is reported. The catalyst was prepared by a co‐precipitation method and characterized using scanning and high‐resolution transmission electron microscopies, energy‐dispersive X‐ray spectroscopy, X‐ray diffraction and surface area measurements. A wide range of alkylarenes were converted to corresponding ketones. The catalyst can be recovered by simple filtration is recyclable for up to six consecutive runs.

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Stability of Cobalt Particles In and Outside HZSM‐5 under CO Hydrogenation Conditions Studied by ex situ and in situ Electron Microscopy

et al. 2020

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Designing stable materials for processes operating under harsh reaction conditions, like CO hydrogenation, is a challenging topic in catalysis. These may provoke several deactivation mechanisms simultaneously, like thermal sintering, oxidation or poisoning of the active sites. We report HZSM‐5 supported cobalt catalysts, exhibiting cobalt nanoparticles encapsulated inside, or located at the exterior of the ZSM‐5 support. The materials were studied by a combination of ex situ and in situ electron microscopy with respect to the growth of the cobalt particles. After 1200 h time on stream under CO hydrogenation conditions, the spent catalyst showed minimal sintering of encapsulated cobalt particles. In situ environmental TEM experiments under model reduction and CO hydrogenation conditions indicate the presence of cobalt nanoparticles, which appear highly resistant towards sintering even up to 700 °C. These results provide a first indication for the preparation of sinter stable catalysts suitable for operating in harsh reaction environments.

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Raising Co/Al2O3 catalyst lifetime in Fischer–Tropsch synthesis by using a novel dual-bed reactor

Cited by 21 publications

References 12 publications

Morphology and deactivation behaviour of Co–Ru/γ‐Al₂O₃ Fischer–Tropsch synthesis catalyst

Morphology and deactivation behaviour of Co–Ru/γ‐Al₂O₃ Fischer–Tropsch synthesis catalyst

Highly selective aerobic oxidation of alkylarenes catalyzed by cobalt‐based nanocatalyst in aqueous solution

Stability of Cobalt Particles In and Outside HZSM‐5 under CO Hydrogenation Conditions Studied by ex situ and in situ Electron Microscopy

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Raising Co/Al2O3 catalyst lifetime in Fischer–Tropsch synthesis by using a novel dual-bed reactor

Cited by 21 publications

References 12 publications

Morphology and deactivation behaviour of Co–Ru/γ‐Al2O3 Fischer–Tropsch synthesis catalyst

Morphology and deactivation behaviour of Co–Ru/γ‐Al2O3 Fischer–Tropsch synthesis catalyst

Highly selective aerobic oxidation of alkylarenes catalyzed by cobalt‐based nanocatalyst in aqueous solution

Stability of Cobalt Particles In and Outside HZSM‐5 under CO Hydrogenation Conditions Studied by ex situ and in situ Electron Microscopy

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Morphology and deactivation behaviour of Co–Ru/γ‐Al₂O₃ Fischer–Tropsch synthesis catalyst

Morphology and deactivation behaviour of Co–Ru/γ‐Al₂O₃ Fischer–Tropsch synthesis catalyst