Genesis of MoS2 from model-Mo-oxide precursors supported on γ-alumina

Sahu, Amit; Steinmann, Stephan N.; Raybaud, Pascal

doi:10.1016/j.jcat.2022.03.007

Cited by 4 publications

(6 citation statements)

References 79 publications

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“…Overall, the structure of two identified intermediates is in a general agreement with other experimental QXAFS results 80,81 and DFT calculations 77 for alumina-supported catalysts. However, Mo ultradispersion and variations of the support lead to significant structural differences.…”

Section: Third Componentsupporting

confidence: 88%

“…Formation of Mo trisulfide oligomers occurs prior to S removal. An optimal path to MoS 2 via Mo trisulfide oligomers was proposed …”

Section: Resultsmentioning

confidence: 99%

“…Scheme of sulfidation steps (as inspired by ref ) and the corresponding MCR-ALS components (see Figures and ).…”

Section: Resultsmentioning

confidence: 99%

“…An optimal path to MoS 2 via Mo trisulfide oligomers was proposed. 77 The intermediate structure should obviously depend on the nature of the supported species and of the support, as well as on the sulfidation conditions. Low loading allows better revealing the support effect.…”

Section: Sulfidation Pathwaysmentioning

confidence: 99%

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Genesis of Active Phase and Support Effect in Ultradispersed Mo Sulfide Catalysts

et al. 2023

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Molybdenum sulfide-based catalysts are widely used for hydrotreatment, hydrogen evolution, and many other reactions. Recently, we demonstrated that not only the edges of MoS 2 slabs but few-atom ultradispersed MoS x clusters also possess high intrinsic activity. However, the structure and genesis of such ultradispersed species remain unknown. Herein, we present a comparative study of MoS x catalysts ultradispersed on different supports (carbons, SiO 2 , Al 2 O 3 , and TiO 2 ). Evolution of the Mo species during sulfidation and hydrodesulfurization (HDS) reaction was studied by means of operando quick X-ray absorption spectroscopy at the Mo K-edge, assisted by chemometric analysis (multivariate curve resolution with alternating least squares). Significant differences of the structure of Mo species and their temperature evolution as a function of support were observed. The sulfidation pathway involves the formation of oxysulfide and sulfur-rich MoS 3 -like intermediates, which are further transformed into the final MoS x clusters. As compared with MoS 2 nanoslabs, the coordination numbers of Mo in the ultradispersed clusters are decreased, and the interatomic Mo−S and Mo−Mo distances are shortened. Other characterizations, in particular, STEM-ADF, confirm that few-atom clusters and single-atom species are predominant in all the catalysts. The materials show high activity per Mo atom in the HDS of thiophene, varying in steps with MoS x dispersion, as determined from XAS, in the sequence: Mo/carbons

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Section: Third Componentsupporting

confidence: 88%

“…Formation of Mo trisulfide oligomers occurs prior to S removal. An optimal path to MoS 2 via Mo trisulfide oligomers was proposed …”

Section: Resultsmentioning

confidence: 99%

“…Scheme of sulfidation steps (as inspired by ref ) and the corresponding MCR-ALS components (see Figures and ).…”

Section: Resultsmentioning

confidence: 99%

Section: Sulfidation Pathwaysmentioning

confidence: 99%

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Genesis of Active Phase and Support Effect in Ultradispersed Mo Sulfide Catalysts

et al. 2023

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“…Abidi et al examined the stability of MoS 2 -edges under electrochemical potential and evidenced possible HER mechanisms including edge reconstructions due to H 2 S-release and involving OH-based HER active sites . Moreover, in the context of the hydrodesulfurization catalyst preparation, small amorphous MoS 3 clusters are known to be intermediate species connecting the Mo oxide precursor to MoS 2 under sulfo-reduction conditions. , However, kinetic limitations could prevent the full sulfidation of such small Mo-clusters, so that some residual oxygen atoms may remain bonded to the Mo-sites . Hence, in an aqueous environment, it may be critical to study the stability of Mo-sites in MoS 3 clusters with respect to H 2 S release and the impact of coordinating oxygen rather than sulfur atoms.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Potential-Dependent Stability and Activity of MoS₃ during the Hydrogen Evolution Reaction

Abidi,

Sahu,

Raybaud

et al. 2023

ACS Catal.

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PtO_xCl_y(OH)_z(H₂O)_n Complexes under Oxidative and Reductive Conditions: Impact of the Level of Theory on Thermodynamic Stabilities

2022

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Platinum-based catalysts with Cl À , OH À , O 2À and H 2 O ligands, are involved in many industrial processes. Their final chemical properties are impacted by calcination and reduction applied during the preparation and activation steps. We investigate their stability under these reactive conditions with density functional theory (DFT). We benchmark various functionals (PBE-dDsC, optPBE, B3LYP, HSE06, PBE0, TPSS, RTPSS and SCAN) against ACFDT-RPA. PBE-dDsC is well adapted, although hybrid functionals are more accurate for redox reactions. Thermody-namic phase diagrams are determined by computing the chemical potential of the species as a function of temperature and partial pressures of H 2 O, HCl, O 2 and H 2 . The stability and nature of the Pt species are highly sensitive to the activation conditions. Under O 2 , high temperatures favour PtO 2 while under H 2 , platinum is easily reduced to Pt(0). Chlorine modifies the coordination sphere of platinum during calcination by stabilizing PtCl 4 and shifts the reduction of platinum to higher temperatures under H 2 .

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Genesis of MoS2 from model-Mo-oxide precursors supported on γ-alumina

Cited by 4 publications

References 79 publications

Genesis of Active Phase and Support Effect in Ultradispersed Mo Sulfide Catalysts

Genesis of Active Phase and Support Effect in Ultradispersed Mo Sulfide Catalysts

Electrochemical Potential-Dependent Stability and Activity of MoS₃ during the Hydrogen Evolution Reaction

PtO_xCl_y(OH)_z(H₂O)_n Complexes under Oxidative and Reductive Conditions: Impact of the Level of Theory on Thermodynamic Stabilities

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Genesis of MoS2 from model-Mo-oxide precursors supported on γ-alumina

Cited by 4 publications

References 79 publications

Genesis of Active Phase and Support Effect in Ultradispersed Mo Sulfide Catalysts

Genesis of Active Phase and Support Effect in Ultradispersed Mo Sulfide Catalysts

Electrochemical Potential-Dependent Stability and Activity of MoS3 during the Hydrogen Evolution Reaction

PtOxCly(OH)z(H2O)n Complexes under Oxidative and Reductive Conditions: Impact of the Level of Theory on Thermodynamic Stabilities

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Product

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Electrochemical Potential-Dependent Stability and Activity of MoS₃ during the Hydrogen Evolution Reaction

PtO_xCl_y(OH)_z(H₂O)_n Complexes under Oxidative and Reductive Conditions: Impact of the Level of Theory on Thermodynamic Stabilities