Reducibility of alumina-supported cobalt Fischer–Tropsch catalysts: Effects of noble metal type, distribution, retention, chemical state, bonding, and influence on cobalt crystallite size

Cook, Kari M.; Poudyal, Samiksha; Miller, Jeffrey T.; Bartholomew, Calvin H.; Hecker, William C.

doi:10.1016/j.apcata.2012.09.032

Cited by 79 publications

(49 citation statements)

References 48 publications

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“…So, for the quantitative study, the first step (Co2AlO4 → CoAl2O4 and CoO) corresponds to Peak 3 and the last two correspond to Peak 4. The ratio between Peaks 4 and 3 is equal to 5 which is in accordance with the literature [39,[41][42][43][44]. The cobalt based catalysts were also characterized by XPS in order to examine the effect of the preparation method on the nature and the oxidation degrees of the surface species.…”

Section: Figure 2 X-ray Diffraction Patterns Of the Mixed Oxidessupporting

confidence: 48%

“…Indeed, a smaller reduction temperature is observed in the case of the solids synthesized using microwaves or ultrasound. Cook et al [44] showed the importance of the crystallite size for the reduction step. Thus, when the crystallite size decreases, the reducibility takes place at lower temperature.…”

Section: Figure 2 X-ray Diffraction Patterns Of the Mixed Oxidesmentioning

confidence: 99%

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Co-Al Mixed Oxides Prepared via LDH Route Using Microwaves or Ultrasound: Application for Catalytic Toluene Total Oxidation

et al. 2015

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Co6Al2HT hydrotalcite-like compounds were synthesized by three different methods: co-precipitation, microwaves-assisted and ultrasound-assisted methods. The mixed oxides obtained after calcination were studied by several techniques: XRD, TEM, H2-TPR and XPS. They were also tested as catalysts in the reaction of total oxidation of toluene. The physico-chemical studies revealed a modification of the structural characteristics (surface area, morphology) as well as of the reducibility of the formed mixed oxides. The solid prepared by microwaves-assisted synthesis was the most active. Furthermore, a relationship between the ratio of Co 2+ on the surface, the reducibility of the Co-Al mixed oxide and the T50 in toluene oxidation was demonstrated. This suggests a Mars Van Krevelen mechanism for toluene total oxidation on these catalysts.

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Section: Figure 2 X-ray Diffraction Patterns Of the Mixed Oxidessupporting

confidence: 48%

Section: Figure 2 X-ray Diffraction Patterns Of the Mixed Oxidesmentioning

confidence: 99%

Co-Al Mixed Oxides Prepared via LDH Route Using Microwaves or Ultrasound: Application for Catalytic Toluene Total Oxidation

et al. 2015

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“…metals and supports used, the size of the supporting particles, dispersion of the active metal on the surface of the support [10,11,12]. The selectivity is related to the properties of the catalyst used but also to a high degree dependent of process parameters used like pressure, temperature, gas composition and gas flow.…”

Section: Introductionmentioning

confidence: 99%

“…The selectivity of a catalyst is described by the probability of chain growth described by the α value, ranging from 0 to a value close to 1. A α value of 0 means that there is no chain growth and the reaction produces methane only; the other extreme is a α value close to 1 when the reaction produces as main products a mixture of predominantly long chained hydrocarbons [11].…”

Section: Introductionmentioning

confidence: 99%

Effect of Calcination Conditions on the Dispersion of Cobalt Over Re, Ru and Rh Promoted Co/γ-Al2O3 Catalysts

et al. 2017

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The effects of catalyst calcination conditions, such as calcination temperature and calcination atmosphere composition on the dispersion of cobalt particles over Co/γ Al O catalysts for Fischer-Tropsch conversion of synthesis gas are studied. A number of catalysts were prepared by incipient wetness impregnation of 20 wt% of cobalt onto γ Al O and promoted with 0.5 wt% ruthenium, rhenium, and rhodium. Metal dispersions of active metals were studied by chemisorption of carbon monoxide. The highest dispersion for Co/ γ Al O catalyst was achieved by calcination at 400 °C in a flow of N . Co metal dispersion seem to be increased in the calcination steps if a flowing gas was used instead of static calcination conditions. The addition of promoter metals like Ru, Re or Rh enhances the dispersion of the active metal.

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“…Factors decreasing the activity of the catalyst are impurities in the feed gas, alkali metal residues in the support or deposits from the syngas, and a poor dispersion of the active metal in the catalyst including sintering of the metal during catalyst use. (Borg et al, 2007, Lillebø et al, 2013, Cook et al, 2012.…”

Section: Introductionmentioning

confidence: 99%

H2-TPR, XPS and TEM Study of the Reduction of Ru and Re promoted Co/γ-Al2O3, Co/TiO2 and Co/SiC Catalysts

Romar¹,

Lillebo²,

Tynjala³

et al. 2016

JMSR

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Effects of Ru and Re promoters on Co-CoO x catalysts supported on γ-Al 2 O 3 , TiO 2 and SiC were investigated to improve the understanding of the role of promoters of the active phase of Co-CoO x -Ru and Co-CoO x -Re. The influence of promoter addition on the composition and activity of the catalysts was characterized by several methods, such as H 2 -TPR, XPS, chemisorption and TEM. Furthermore, the role of support and metal-support interaction was especially studied and different support materials were compared.Based on the results, addition of promoter metals (Ru or Re) will most likely improve catalytic activity of Co/γ-Al 2 O 3 , Co/TiO 2 and Co/SiC catalysts by increasing the active metal surface available for chemical reaction and by decreasing the size of the metallic nanoparticles. These changes in the catalytic activity were also associated with the changes in the ratio of metal and metal oxide phases in the surface composition as observed by XPS. Promoter metals also decreased the reduction temperatures needed for the reduction of Co 3 O 4 to CoO and further to metallic cobalt. Significant decrease in reduction temperature was observed especially when ruthenium was used as the promoter.

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Reducibility of alumina-supported cobalt Fischer–Tropsch catalysts: Effects of noble metal type, distribution, retention, chemical state, bonding, and influence on cobalt crystallite size

Cited by 79 publications

References 48 publications

Co-Al Mixed Oxides Prepared via LDH Route Using Microwaves or Ultrasound: Application for Catalytic Toluene Total Oxidation

Co-Al Mixed Oxides Prepared via LDH Route Using Microwaves or Ultrasound: Application for Catalytic Toluene Total Oxidation

Effect of Calcination Conditions on the Dispersion of Cobalt Over Re, Ru and Rh Promoted Co/γ-Al2O3 Catalysts

H2-TPR, XPS and TEM Study of the Reduction of Ru and Re promoted Co/γ-Al2O3, Co/TiO2 and Co/SiC Catalysts

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