The Role of Structural Carbon in Transition Metal Sulfides Hydrotreating Catalysts

Berhault, Gilles; Mehta, Apurva; Pavel, Alexandru C.; Yang, Jingxuan; Rendón, L.; Yacamán, Miguel José; Cota‐Araiza, L.; Duarte-Möller, A.; Chianelli, Russell R.

doi:10.1006/jcat.2000.3124

Cited by 116 publications

(83 citation statements)

References 46 publications

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“…Indeed, in typical hydotreating conditions, carbide and sulphide catalysts would tend to common active specific presenting both S and C moieties, as already has been reported by different authors [8-10, 16, 18-20]. The formation of surface carbide-like entities was clearly observed by Berhault and co-workers [17] using NEXAFS on MoS 2 catalyzing the HDS of DBT. Consequently, the formation of ''structural'' carbon replacing surface sulphur atoms at the edges of the layers and taking part in the active phase may be envisaged in the present case.…”

Section: Discussionsupporting

confidence: 50%

Nickel-Molybdenum-Tungsten Sulfide catalysts prepared by in situ activation of tri-metallic (Ni-Mo-W) alkylthiomolybdotungstates

2005

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Unsupported nickel-molybdenum-tungsten sulphide catalysts were prepared from tri-metallic Ni-Mo-W alkyl precursors by in situ activation during the hydrodesulphurization (HDS) of dibenzothiophene (DBT). The tri-metallic Ni-Mo-W precursors were prepared by reaction of tetraalkylammonium thiomolibdotungstates salts, (R 4 N) 4 MoWS 8 (where R = H, methyl, propyl, butyl, cetyl-trimetyl), with NiCl 2 in water at a Ni/Mo(W) molar ratio of 2. These precursors are named Ni/(NH 4 ) C 1 , NiMoW-C 3 , NiMoW-C 4 and NiMoW-C C catalysts respectively. These catalysts exhibit a ''Swiss-cheese''-like morphology, a wide distribution of specific areas (from 46.9-194.07 m 2 /g) and high content of carbon (C/Mo = 2.5-8.9). The in situ activation of these tetraalkylammonium thiotrimetallates precursors leads to a mesoporous structure with pore size ranging from 10-40 Å and type IV adsorption-desorption isotherms of nitrogen. X-ray diffraction showed that the structure of unsupported nickelmolybdenum-tungsten sulphide catalysts corresponds to a typical structure of 2H-MoS 2 poorly crystalline with low-stacked layers. The nature of the alkyl group strongly affects both the specific area and the HDS activity. The catalytic activity is strongly enhanced when using carbon-containing precursors; the NiMoW catalysts prepared by in situ activation present high HDS activity. The lowest specific area of the catalysts was observed for the NiMoW-H sample.

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Section: Discussionsupporting

confidence: 50%

Nickel-Molybdenum-Tungsten Sulfide catalysts prepared by in situ activation of tri-metallic (Ni-Mo-W) alkylthiomolybdotungstates

2005

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“…The stoichiometry in this case is MoS 1.88 C 1.12 . Although, the exact structure of the edge carbide is not known the carbiding of MoS 2 edge plane is supported by synchrotron studies of catalysts stabilized in HDS conditions [33]. In this study, carbon edge X-ray absorption studies clearly indicated, through the measurement of Auger electrons emanating from the catalyst surface as a function of x-ray energy, that the surfaces of MoC and the stabilized MoS 2 catalysts were identical.…”

Section: The Catalytically Stable States Of Mos 2 Based Catalystmentioning

confidence: 63%

Periodic Trends Transition Metal Sulfide Catalysis: Intuition and Theory

Chianelli¹

2006

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Évolution des propriétés catalytiques en hydrodésulfurisation en fonction de la position du métal de transition dans la classification périodique : intuition et théorie -Le besoin d'hydrogé-ner du charbon afin d'obtenir des combustibles liquides devenant pressant dans les années 1920, des catalyseurs constitués de sulfure de métal de transition (TMS) ont été utilisés. Sabatier a reçu le prix Nobel en 1912 pour avoir décrit le phénomène d'hydrogénation par des métaux de transition. Cependant, lorsque les métaux de transition étaient utilisés pour hydrogéner du charbon, les TMS apparaissaient comme des états catalytiques stables en raison de leur teneur élevée en sulfure dans les liquides dérivés du charbon. À partir des années 1920 -1930. a testé plus de 6000 catalyseurs. C'est à partir de là que le Co (Ni)/Mo/Al 2 O 3 moderne est apparu.Depuis, les scientifiques nous ont permis de mieux comprendre les propriétés fondamentales qui conduisent à la fois à l'activité des sulfures binaires simples et au mécanisme par lequel deux métaux (Co + Mo) agissent de façon concomitante pour favoriser l'activité (promotion). Les efforts de départ se concentraient sur les catalyseurs commerciaux supportés avec un succès limité. Au début des années 1980, des évolutions des propriétés catalytiques en hydrodésulfurisation selon la position du métal de transition dans la classification périodique sur des catalyseurs non supportés, ont été découvertes et ces résultats sont à la base d'une compréhension basique supplémentaire des propriétés-clés qui ont conduit à l'activité catalytique. Ces résultats ont été enrichis de données complémentaires obtenues lors de recherches menées au fil des années afin d'inclure des catalyseurs supportés et de nombreux substrats à base de pétrole.Des résultats précédemment obtenus reliaient l'activité catalytique aux chaleurs de formation des sulfures et au caractère d (échelle de Pauling) des métaux de transition. Ces corrélations ont mis en évidence à la fois l'importance des électrons 4d et 5d mais également le principe catalytique bien établi selon lequel les liaisons du sulfure de métal nécessitaient d'être « juste bien établies », ni trop fortes ni trop faibles permettant ainsi une rotation facile des molécules d'adsorption et de désorption. La moyenne des chaleurs de formation de Co 9 S 8 et MoS 2 suggérait que la promotion se produisait à travers les lacunes laissées par le sulfure et que la formation était réalisée par les atomes qui partageaient à la fois un atome Co et un atome Mo sur la surface.Des études théoriques ont également commencé à cette période qui renforçaient encore plus l'idée que les électrons d se trouvant dans les orbitales frontières des catalyseurs avaient un rôle-clé pour déterminer la catalyse à la surface. Le succès de cette approche s'explique par le fait qu'elle unifiait les systèmes de TMS promus avec les TMS binaires et offrait une logique commune pour les deux activités. Des progrès Research Advances in Rational Design of Catalysts and Sorbents Avancées de l...

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“…42 Previous studies have also shown that bending of the layers led to higher (110)/(100) intensity ratios than expected from a perfectly crystalline bulk sample (I(110)/I(100) = 0.52). 26,43 The actual I(110)/I(100) ratio (0.60) is slightly higher than the expected value for highly crystalline bulk MoS 2 suggesting that bending of the layers occurs either from a minor proportion of very bent slabs or from a large proportion of slabs but with small bending angles.…”

Section: Characterization By N 2 Adsorption Xrd Xps and (Hr)temmentioning

confidence: 73%

“…The last point to consider in a future study will be the influence of the replacement of sulfur by carbide-like entities as observed in steady-state DBT HDS stabilized catalysts and also to determine how DBT molecules can interact with these interfacial sites in order to perform HDS reaction. 26,27 …”

Section: Significance Of the Present Interface Model Compared To Prevmentioning

confidence: 99%

HRTEM and molecular modeling of the MoS₂–Co₉S₈interface: understanding the promotion effect in bulk HDS catalysts

Ramos

Berhault

Ferrer

et al. 2012

Catal. Sci. Technol.

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143

100

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As environmental regulations increase, more selective transition metal sulfide (TMS) catalytic materials for hydrotreating applications are needed. Highly active TMS catalysts become more and more desirable triggering new interest for unsupported Co-promoted MoS 2 -based systems that have high volumetric activity as reported here. Contrary to the common observation for alumina-supported MoS 2 -based catalysts, we found in our previous studies with dibenzothiophene (DBT) hydrodesulfurization (HDS) that the catalytic activity is directly proportional to the increase of surface area of the sulfide phases (Co 9 S 8 and MoS 2 ) present in Co-promoted MoS 2 unsupported catalysts. This suggests that activity is directly connected with an increase of the contact surface area between the two sulfide phases. Understanding of the nature of the possible interaction between MoS 2 and Co 9 S 8 in unsupported catalytic systems is therefore critical in order to get a more generalized overview of the causes for synergy. This has been achieved herein through the detailed characterization by XRD, XPS, and HRTEM of the highly active Co 9 S 8 / MoS 2 catalyst resulting in a proposed model for a Co 9 S 8 /MoS 2 interface. This model was then subjected to a DFT analysis to determine a reasonable description of the surface contact region between the two bulk phases. Modelling of the interface shows the creation of open latent vacancy sites on Mo atoms interacting with Co and formation of direct Co-Mo bonds. Strong electron donation from Co to Mo also occurs through the intermediate sulfur atom bonded to both metals while an enhanced metallic character is also found. These changes in coordination and electronic properties are expected to favor a synergetic effect between Co and Mo at the proposed localized interface region between the two bulk MoS 2 and Co 9 S 8 phases.

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The Role of Structural Carbon in Transition Metal Sulfides Hydrotreating Catalysts

Cited by 116 publications

References 46 publications

Nickel-Molybdenum-Tungsten Sulfide catalysts prepared by in situ activation of tri-metallic (Ni-Mo-W) alkylthiomolybdotungstates

Nickel-Molybdenum-Tungsten Sulfide catalysts prepared by in situ activation of tri-metallic (Ni-Mo-W) alkylthiomolybdotungstates

Periodic Trends Transition Metal Sulfide Catalysis: Intuition and Theory

HRTEM and molecular modeling of the MoS₂–Co₉S₈interface: understanding the promotion effect in bulk HDS catalysts

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The Role of Structural Carbon in Transition Metal Sulfides Hydrotreating Catalysts

Cited by 116 publications

References 46 publications

Nickel-Molybdenum-Tungsten Sulfide catalysts prepared by in situ activation of tri-metallic (Ni-Mo-W) alkylthiomolybdotungstates

Nickel-Molybdenum-Tungsten Sulfide catalysts prepared by in situ activation of tri-metallic (Ni-Mo-W) alkylthiomolybdotungstates

Periodic Trends Transition Metal Sulfide Catalysis: Intuition and Theory

HRTEM and molecular modeling of the MoS2–Co9S8interface: understanding the promotion effect in bulk HDS catalysts

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Product

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HRTEM and molecular modeling of the MoS₂–Co₉S₈interface: understanding the promotion effect in bulk HDS catalysts