Location and coordination of promoter atoms in Co- and Ni-promoted MoS2-based hydrotreating catalysts

Lauritsen, Jeppe V.; Kibsgaard, Jakob; Olesen, Georg H.; Moses, Poul Georg; Hinnemann, Berit; Helveg, Stig; Nørskov, Jens K.; Clausen, Bjerne S.; Topsøe, Henrik; Lægsgaard, Erik; Besenbacher, Flemming

doi:10.1016/j.jcat.2007.04.013

Cited by 455 publications

(393 citation statements)

References 74 publications

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“…This preferential location of Co is also supported by other DFT simulations [26] and scanning tunnel microscopy (STM) experiments on gold supported CoMoS [27]. This latter cutting edge technique brought also numerous insights consistent with DFT approaches on the local structures of the active phases [28].…”

Section: Introductionsupporting

confidence: 72%

“…This point will be analyzed in details in the paper by K. Marchand et al published in the present volume [82]. Recent STM experiments have also revealed the presence of mixed Ni-Mo sites on the edges of NiMoS nano-crystallites [28], whereas such a situation has not been observed for CoMoS [65]. There is thus a striking agreement between the DFT calculations and STM experiments, which both reveal that Co prefers to be located at the S-edge, whereas Ni is present on both S-and M-edge.…”

Section: Nano-crystallite Morphologiesmentioning

confidence: 67%

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A DFT Study of CoMoS and NiMoS Catalysts: from Nano-Crystallite Morphology to Selective Hydrodesulfurization

Krebs

Daudin²,

Raybaud³

2009

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Étude DFT des catalyseurs CoMoS et NiMoS : de la morphologie des nano-cristallites à l'hydrodésulfuration sélective -Cet article présente des résultats récents obtenus dans des études utilisant la théorie de la fonctionnelle de la densité (DFT) pour la caractérisation à l'échelle atomique des phases actives Co(Ni)MoS utilisées en catalyse d'hydrodésulfuration (HDS) sélective. L'effet des conditions du milieu réactionnel sulfo-réducteur sur la stabilité et la nature des sites actifs localisés au bord des nano-cristallites Co(Ni)MoS est mis en évidence. En combinant les calculs DFT et un modèle thermodynamique, il apparaît que la teneur en promoteur sur les bords des cristallites en conjonction avec la morphologie des cristallites dépend des conditions sulfo-réductrices. Nous montrons ensuite comment la nature des sites actifs Co(Ni)Mo influence l'HDS sélective de molécules soufrées légères (alkylthiophènes) vis-à-vis de l'hydrogénation (HydO) des oléfines légères (alkyl-butènes). La combinaison des calculs DFT d'adsorption de deux molécules modèles (2-méthyl-thiophène et 2,3-diméthyl-but-1-ène) avec la modélisation cinétique de la sélectivité HDS/HydO permet de proposer une explication de l'origine de cette sélectivité basée sur la compétition d'adsorption des réactifs. Abstract -A DFT Study of CoMoS and NiMoS Catalysts from Nano-Crystallite Morphology to Selective Hydrodesulfurization -This paper reports an overview of recent DFT studies on the atomic scale characterization of Co(Ni)MoS active phases used in selective hydrodesulfurization (HDS) catalysis. A peculiar attention is paid to the effect of the sulfo-reductive reaction conditions on the

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Section: Introductionsupporting

confidence: 72%

Section: Nano-crystallite Morphologiesmentioning

confidence: 67%

A DFT Study of CoMoS and NiMoS Catalysts: from Nano-Crystallite Morphology to Selective Hydrodesulfurization

Krebs

Daudin²,

Raybaud³

2009

Oil & Gas Science and Technology - Rev. IFP

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“…Nowadays, the most widely accepted model for the structure of promoted HDS catalysts is the model developed by Topsøe [25]. It was reported that Co substitutes Mo atoms at the S edge creating a tetrahedral environment of Co (Co-Mo-S edge) [26], and it was shown for CoMoS phases that a S atom having bonds to Mo and Co is less strong bound than a S atom with bonds to two Mo atoms and therefore such a S atoms can be removed easily creating a vacancy [25]. The presence of Co located on the MoS 2 slabs confirmed by EDS analyses (see HRTEM) indicates the formation of the CoMoS phase.…”

Section: Discussionmentioning

confidence: 99%

Preparation and Characterization of SBA-15 Supported Cobalt–Molybdenum Sulfide Catalysts for HDS Reaction: An All Sulfide Route to Hydrodesulfurization Catalysts

et al. 2008

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MoS 2 hydrodesulfurization (HDS) catalysts promoted with Co supported on SBA-15 were synthesized from sulfur-containing Mo sources [ammonium thiomolybdate (ATM), and tetramethylammonium thiomolybdate (TMATM)] and Co complexes cobalt dimethylthiocarbamate by using different synthesis strategies in order to achieve active catalysts. The (Co)-MoS 2 /SBA-15 catalysts were characterized with X-ray diffraction, N 2 -physisorption and High-Resolution Transmission Electron Microscopy. The catalytic performance in the HDS reaction of dibenzothiophene was examined at T = 623 K and P H2 = 3.4 MPa. The results of the experiments suggest that the sequence of impregnation steps has no significant influence on the HDS activity. On the other hand, the use of different thiomolybdate precursors significantly affects the catalytic activity. The catalysts derived from TMATM show lower HDS activities compared to the catalysts synthesized from ATM which is probably due to the presence of pronounced pore blocking as well as the generation of big needle-like aggregates of the Co-MoS 2 phase. It seems that the formation of intermediate MoS 3 is not a prerequisite for the generation of catalytic active CoMoS phases. The high activity and high selectivity for the direct desulfurization pathway of catalysts prepared with ATM despite the large MoS 2 stacking could be due to the generation of a large number of coordinately unsaturated sites.

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“…* cesar.gonzalez.pascual@gmail.com Different kinds of defects can be produced during the growth process [24], leading to a change in the electronic, magnetic, or optical properties [22,[25][26][27]. The defects can be classified into three types: point defects (such as vacancies or antisites), grain boundaries, and external borders of the compound.…”

Section: Introductionmentioning

confidence: 99%

Molecular detection on a defective MoS2 monolayer by simultaneous conductance and force simulations

González

Dappe

2017

Phys. Rev. B

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Based on simultaneous force and conductance simulations, a proof of concept for a potential method of molecular detection is presented. Using density functional theory calculations, a metallic tip has been approached to different small inorganic molecules such as CO, CO 2 , H 2 O, NO, N 2 , or O 2 . The molecules have been previously chemisorbed on a defect formed by two Mo atoms occupying a S divacancy on a MoS 2 monolayer where they are strongly bonded to the topmost substitutional molybdenum. At that site, the fixed molecules can be imaged by a conductive atomic-force-microscopy tip. Due to the differences in atomic composition and electronic configurations, each molecule yields specific conductance/force curves during the tip approach. A molecule-tip contact is established at the force minimum, followed by the formation of a characteristic plateau in the conductance in most of the cases. Focusing our attention on the position and values of such force minimum and conductance maximum, we can conclude that both characteristic properties can give a clear signature of each molecule, proposing a different method of detecting molecules adsorbed on highly reactive sites.

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Location and coordination of promoter atoms in Co- and Ni-promoted MoS2-based hydrotreating catalysts

Cited by 455 publications

References 74 publications

A DFT Study of CoMoS and NiMoS Catalysts: from Nano-Crystallite Morphology to Selective Hydrodesulfurization

A DFT Study of CoMoS and NiMoS Catalysts: from Nano-Crystallite Morphology to Selective Hydrodesulfurization

Preparation and Characterization of SBA-15 Supported Cobalt–Molybdenum Sulfide Catalysts for HDS Reaction: An All Sulfide Route to Hydrodesulfurization Catalysts

Molecular detection on a defective MoS2 monolayer by simultaneous conductance and force simulations

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