The effect of sulphidation on the nature of active sites on nickel-molybdenum-alumina hydrorefining catalysts

1983 ◽  
Vol 48 (8) ◽  
pp. 2269-2272 ◽  
Author(s):  
Rafael López
Keyword(s):  
Active Sites ◽  
Strong Influence ◽  
Hydrotreating Catalysts

A strong influence of sulphidation on the hydrogenation and hydrogenolytic activity of Mo-Al2O3 and Ni-Mo-Al2O3 hydrotreating catalysts has been found. Two kinds of active sites are distinguished, the first consisting of surface molybdenum atoms and serving mostly for hydrogenation, the second type formed by interaction of Mo with Ni atoms and being active in sulphided form for direct hydrogenolysis of the C-S bonds.

Structure and Nature of the Active Sites in CoMo Hydrotreating Catalysts Conversion of Thiophene

1998 ◽  
Vol 175 (1) ◽  
pp. 108-116 ◽  
Author(s):  
R.G. Leliveld ◽  
A.J. van Dillen ◽  
J.W. Geus ◽  
D.C. Koningsberger
Keyword(s):  
Active Sites ◽  
Hydrotreating Catalysts

scholarly journals Probing the Active Sites of MoS2 Based Hydrotreating Catalysts Using Modulation Excitation Spectroscopy

ACS Catalysis ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 2568-2579 ◽  
Author(s):  
Abhijeet Gaur ◽  
Trine Marie Hartmann Dabros ◽  
Martin Høj ◽  
Alexey Boubnov ◽  
Tim Prüssmann ◽  
...  
Keyword(s):  
Active Sites ◽  
Hydrotreating Catalysts ◽  
Modulation Excitation Spectroscopy ◽  
Modulation Excitation

scholarly journals Structure and Nature of the Active Sites in CoMo Hydrotreating Catalysts. An EXAFS Study of the Reaction with Selenophene

1997 ◽  
Vol 101 (51) ◽  
pp. 11160-11171 ◽  
Author(s):  
Bob R. G. Leliveld ◽  
Jos A. J. van Dillen ◽  
John W. Geus ◽  
Diek C. Koningsberger ◽  
Mark de Boer
Keyword(s):  
Active Sites ◽  
Hydrotreating Catalysts ◽  
Exafs Study

scholarly journals Nature of active sites in Ni2P hydrotreating catalysts as probed by iron substitution

2015 ◽  
Vol 164 ◽  
pp. 204-216 ◽  
Author(s):  
Haiyan Zhao ◽  
S. Ted Oyama ◽  
Hans-Joachim Freund ◽  
Radosław Włodarczyk ◽  
Marek Sierka
Keyword(s):  
Active Sites ◽  
Hydrotreating Catalysts ◽  
Iron Substitution

scholarly journals Using Transient XAS to Detect Minute Levels of Reversible S-O Exchange at the Active Sites of MoS2-Based Hydrotreating Catalysts: Effect of Metal Loading, Promotion, Temperature, and Oxygenate Reactant

ACS Catalysis ◽  
2021 ◽  
pp. 633-647
Author(s):  
Abhijeet Gaur ◽  
Matthias Stehle ◽  
Marc-André Serrer ◽  
Magnus Zingler Stummann ◽  
Camille La Fontaine ◽  
...  
Keyword(s):  
Active Sites ◽  
Hydrotreating Catalysts ◽  
Metal Loading

Effect of strain on ADF-STEM high-resolution images

1991 ◽  
Vol 49 ◽  
pp. 666-667
Author(s):  
M. Kelly ◽  
D.M. Bird
Keyword(s):  
High Resolution ◽  
Strong Influence ◽  
Intensity Variation ◽  
Dark Field ◽  
Atomic Resolution ◽  
Strain Fields ◽  
High Resolution Image ◽  
Annular Dark Field ◽  
High Resolution Images ◽  
Interesting Alternative

It is well known that strain fields can have a strong influence on the details of HREM images. This, for example, can cause problems in the analysis of edge-on interfaces between lattice mismatched materials. An interesting alternative to conventional HREM imaging has recently been advanced by Pennycook and co-workers where the intensity variation in the annular dark field (ADF) detector is monitored as a STEM probe is scanned across the specimen. It is believed that the observed atomic-resolution contrast is correlated with the intensity of the STEM probe at the atomic sites and the way in which this varies as the probe moves from cell to cell. As well as providing a directly interpretable high-resolution image, there are reasons for believing that ADF-STEM images may be less suseptible to strain than conventional HREM. This is because HREM images arise from the interference of several diffracted beams, each of which is governed by all the excited Bloch waves in the crystal.

What catalysis needs from the electron microscopist

1988 ◽  
Vol 46 ◽  
pp. 694-695
Author(s):  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Catalyst Deactivation ◽  
Surface Composition ◽  
Internal Surface ◽  
Active Phase ◽  
Atomic Scale ◽  
Metal Catalyst ◽  
Internal Surface Area ◽  
Porous Support

Heterogeneous catalysts, used in industry for the production of fuels and chemicals, are microporous solids characterized by a high internal surface area. The catalyticly active sites may occur at the surface of the bulk solid or of small crystallites deposited on a porous support. An example of the former case would be a zeolite, and of the latter, a supported metal catalyst. Since the activity and selectivity of a catalyst are known to be a function of surface composition and structure, it is highly desirable to characterize catalyst surfaces with atomic scale resolution. Where the active phase is dispersed on a support, it is also important to know the dispersion of the deposited phase, as well as its structural and compositional uniformity, the latter characteristics being particularly important in the case of multicomponent catalysts. Knowledge of the pore size and shape is also important, since these can influence the transport of reactants and products through a catalyst and the dynamics of catalyst deactivation.

Scanning luminescence x-ray microscopy: Progress toward selective staining using microspheres

1994 ◽  
Vol 52 ◽  
pp. 74-75
Author(s):  
C. Jacobsen ◽  
J. Fu ◽  
S. Mayer ◽  
Y. Wang ◽  
S. Williams
Keyword(s):  
Visible Light ◽  
Active Sites ◽  
Light Emission ◽  
Chinese Hamster ◽  
Polystyrene Spheres ◽  
Good Resistance ◽  
X Ray ◽  
Selective Staining ◽  
Visible Light Emission ◽  
Specific Labelling

In scanning luminescence x-ray microscopy (SLXM), a high resolution x-ray probe is used to excite visible light emission (see Figs. 1 and 2). The technique has been developed with a goal of localizing dye-tagged biochemically active sites and structures at 50 nm resolution in thick, hydrated biological specimens. Following our initial efforts, Moronne et al. have begun to develop probes based on biotinylated terbium; we report here our progress towards using microspheres for tagging.Our initial experiments with microspheres were based on commercially-available carboxyl latex spheres which emitted ~ 5 visible light photons per x-ray absorbed, and which showed good resistance to bleaching under x-ray irradiation. Other work (such as that by Guo et al.) has shown that such spheres can be used for a variety of specific labelling applications. Our first efforts have been aimed at labelling ƒ actin in Chinese hamster ovarian (CHO) cells. By using a detergent/fixative protocol to load spheres into cells with permeabilized membranes and preserved morphology, we have succeeded in using commercial dye-loaded, spreptavidin-coated 0.03μm polystyrene spheres linked to biotin phalloidon to label f actin (see Fig. 3).

Grain separation enhanced magnetic coercivity in Pt/Co multilayers.

1993 ◽  
Vol 51 ◽  
pp. 1038-1039 ◽  
Author(s):  
G.A. Bertero ◽  
R. Sinclair
Keyword(s):  
Remanent Magnetization ◽  
Strong Influence ◽  
Uniaxial Anisotropy ◽  
Magnetic Coupling ◽  
Recording Media ◽  
Magnetic Media ◽  
Signal To Noise ◽  
Out Of Plane ◽  
Longitudinal Recording ◽  
The Relationship

Pt/Co multilayers displaying perpendicular (out-of-plane) magnetic anisotropy and 100% perpendicular remanent magnetization are strong candidates as magnetic media for the next generation of magneto-optic recording devices. The magnetic coercivity, Hc, and uniaxial anisotropy energy, Ku, are two important materials parameters, among others, in the quest to achieving higher recording densities with acceptable signal to noise ratios (SNR). The relationship between Ku and Hc in these films is not a simple one since features such as grain boundaries, for example, can have a strong influence on Hc but affect Ku only in a secondary manner. In this regard grain boundary separation provides a way to minimize the grain-to-grain magnetic coupling which is known to result in larger coercivities and improved SNR as has been discussed extensively in the literature for conventional longitudinal recording media.We present here results from the deposition of two Pt/Co/Tb multilayers (A and B) which show significant differences in their coercive fields.

The design and catalytic performance of molybdenum active sites on an MCM-41 framework for the aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

2019 ◽  
Vol 9 (3) ◽  
pp. 811-821 ◽  
Author(s):  
Zhao-Meng Wang ◽  
Li-Juan Liu ◽  
Bo Xiang ◽  
Yue Wang ◽  
Ya-Jing Lyu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Aerobic Oxidation ◽  
Catalytic Performance ◽  
Mcm 41

The catalytic activity decreases as –(SiO)3Mo(OH)(O) > –(SiO)2Mo(O)2 > –(O)4–MoO.

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