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Sonja Eijsbouts – One of the best experts on this subject based on the ideXlab platform.

  • Electron Tomography Reveals the Active Phase–Support Interaction in Sulfidic Hydroprocessing Catalysts
    ACS Catalysis, 2017
    Co-Authors: Sonja Eijsbouts, Jana Juan-alcaniz, Leon C. A. Van Den Oetelaar, Jaap A. Bergwerff, Joachim Loos, Anna Carlsson, Eelco T. C. Vogt
    Abstract:

    Conventional two-dimensional (2D) transmission electron microscopy of sulfidic hydroprocessing catalysts can be deceiving and give the impression that parts of the support are overloaded with Active Phase. High-angle annular dark field scanning transmission electron microscopy tomography reveals details on the morphology of MoS2 crystallites and their interaction with the Al2O3 and TiO2 support particles. The three-dimensional (3D) reconstruction shows that the Active Phase is mainly present as MoS2 single slabs of various shapes aligned with the support. It becomes clear that the surface of the support particles is, in fact, only partly covered by the Active Phase and the pores remain accessible for reactant molecules.

  • on the flexibility of the Active Phase in hydrotreating catalysts
    Applied Catalysis A-general, 1997
    Co-Authors: Sonja Eijsbouts
    Abstract:

    Abstract This review deals with the structure of the Active Phase in sulfidic Co Mo and Ni Mo hydrotreating catalysts. Various models describing the catalyst and its interaction with the reaction environment are discussed in the light of the evolution of the Active Phase during the catalyst life cycle. Special attention is paid to the contribution of Mossbauer Emission Spectroscopy (MES), Extended X-ray Absorption Fine Structure (EXAFS), High Resolution Transmission Electron Microscopy (HR-TEM) and Molecular Modeling to the unraveling of the Active Phase structure. It is concluded that MoS 2 sintering and Co 9 S 8 (Ni 3 S 2 , NiS) segregation during the catalyst life cycle force the shift of the actual reaction mechanism from that involving a single site or an ensemble of sites to that of a close cooperation between segregated components. The adsorption of reactants can take place in many diferent ways, through the heteroatom or through the ring, on the Mo sites as well as on the Co (Ni) sites. The exact state of each Active site depends on the reaction environment. If the catalyst is S deficient, the classical adsorption mechanism involving the S vacancy is dominant. With a fully sulfided catalyst surface the adsorption takes place through S S bonds. The catalyst is a dynamic evolving system adapting itself to its ever changing reaction environment. Each catalyst component fulfills multiple functions in determining the catalyst structure as well as its interaction with the reactant molecules.

Eelco T. C. Vogt – One of the best experts on this subject based on the ideXlab platform.

  • Electron Tomography Reveals the Active Phase–Support Interaction in Sulfidic Hydroprocessing Catalysts
    ACS Catalysis, 2017
    Co-Authors: Sonja Eijsbouts, Jana Juan-alcaniz, Leon C. A. Van Den Oetelaar, Jaap A. Bergwerff, Joachim Loos, Anna Carlsson, Eelco T. C. Vogt
    Abstract:

    Conventional two-dimensional (2D) transmission electron microscopy of sulfidic hydroprocessing catalysts can be deceiving and give the impression that parts of the support are overloaded with Active Phase. High-angle annular dark field scanning transmission electron microscopy tomography reveals details on the morphology of MoS2 crystallites and their interaction with the Al2O3 and TiO2 support particles. The three-dimensional (3D) reconstruction shows that the Active Phase is mainly present as MoS2 single slabs of various shapes aligned with the support. It becomes clear that the surface of the support particles is, in fact, only partly covered by the Active Phase and the pores remain accessible for reactant molecules.

Brian M. Mercer – One of the best experts on this subject based on the ideXlab platform.

  • Differences in women presenting in latent and Active Phase of labor
    American Journal of Obstetrics and Gynecology, 2003
    Co-Authors: Jennifer L. Bailit, Leroy J. Dierker, Brian M. Mercer
    Abstract:

    Phase OF LABOR JENNIFER BAILIT, LEROY DIERKER, BRIAN MERCER, MetroHealth Medical Center, Case Western Reserve University, Obstetrics/Gynecology, Cleveland, OH OBJECTIVE: Women presenting in latent Phase are at increased risk for Cesarean (CD) than those presenting in Active Phase. We sought to evaluate patient, labor, management and outcome differences between those presenting in latent Phase and Active Phase. STUDY DESIGN: We evaluated all low-risk singleton, term women with vertex presentations, presenting in Active Phase (AP: contractions with or without ROM > = 4 cm) or latent Phase (LP: contractions with or without ROM