Voronoi cells: An interesting and potentially useful cell model for interpreting the small-angle scattering of catalysts

1983 ◽  
Vol 16 (1) ◽  
pp. 83-88 ◽  
Author(s):  
H. Brumberger ◽  
J. Goodisman
Keyword(s):  
Small Angle ◽  
Heterogeneous Catalysts ◽  
Structural Model ◽  
Cell Model ◽  
Voronoi Cells ◽  
X Ray ◽  
Surface Areas ◽  
Angle Scattering ◽  
Metallic Catalyst ◽  
Polyhedral Cells

A structural model, based on Voronoi polyhedral cells partly filled with support and metallic catalyst, is proposed for interpreting the small-angle X-ray scattering of heterogeneous catalysts. The model's properties are described, and the model is applied to porous Al2O3 and Pt/porous Al2O3. Surface areas calculated from the X-ray data by means of the statistical geometry of Voronoi tesselations are found in good agreement with those determined by BET (Brunauer, Emmett & Teller) adsorption methods.

Small-Angle Scattering of Heterogeneous Catalysts

1997 ◽  
Vol 30 (5) ◽  
pp. 647-652 ◽  
Author(s):  
A. Benedetti
Keyword(s):  
Small Angle ◽  
Heterogeneous Catalysts ◽  
Small Angle Scattering ◽  
Organic Films ◽  
Supported Metal Catalysts ◽  
General Picture ◽  
Surface Areas ◽  
Morphological Aspects ◽  
Angle Scattering ◽  
Three Phase

A heterogeneously catalyzed reaction involves the adsorption of the reactants on the surface of the catalyst. Consequently, catalytic activity is usually strongly related to the microstructural features of the catalyst. Small-angle scattering (SAS) has been extensively used to study heterogeneous catalysts and it has been shown to provide useful information about the specific surface of the active phases. In particular, the majority of the research has dealt, and still deals, with supported metal catalysts, which are three-phase systems (support, voids and metal). Several attempts have been made experimentally and theoretically to overcome this problem and to obtain values for the three surface areas. In the first part of the paper, earlier results and recent approaches will be reviewed in order to give a general picture of the problem. In the second part, some recent results on other kinds of heterogeneous catalysts, such as sulfated zirconia, with strongly acidic properties, and functionalized silicas, will be discussed. Knowledge of the degree of smoothness of the particles (angularity) and thickness of the organic films obtained by SAS experiments can be very useful in clarifying morphological aspects of these porous systems.

Neutron and X-ray small-angle scattering with Fe-based metallic glasses

1988 ◽  
Vol 97 ◽  
pp. 227-230 ◽  
Author(s):  
P. Lamparter ◽  
S. Steeb ◽  
D.M. Kroeger ◽  
S. Spooner
Keyword(s):  
Metallic Glasses ◽  
Small Angle ◽  
Small Angle Scattering ◽  
X Ray ◽  
Angle Scattering

Dimensions de micelles mixtes de p-alkylbenzènesulfonates par diffusion central des rayons X

1977 ◽  
Vol 10 (1) ◽  
pp. 37-44 ◽  
Author(s):  
C. Cabos ◽  
P. Delord ◽  
J. Rouviere
Keyword(s):  
Small Angle ◽  
Small Angle Scattering ◽  
Micellar Solutions ◽  
Probable Structure ◽  
X Ray ◽  
Absolute Scale ◽  
Angle Scattering ◽  
Scattering Measurements ◽  
Two Component ◽  
Most Probable Structure

The structure of micellar solutions is determined from X-ray small-angle scattering measurements on an absolute scale. The most probable structure is chosen by comparison with spherical cylindrical and lamellar models. This method is applied to two-component micelles and it is possible to follow the variation of micellar dimensions when the concentration of each component is varying.

Evidence of polyion hydration from X-ray and neutron small-angle scattering experiments

1981 ◽  
Vol 4 (4) ◽  
pp. 225-231 ◽  
Author(s):  
J. Pleštil ◽  
J. Mikeš ◽  
K. Dušek ◽  
Ju. M. Ostanevich ◽  
A. B. Kunchenko
Keyword(s):  
Small Angle ◽  
Small Angle Scattering ◽  
X Ray ◽  
Angle Scattering ◽  
Neutron Small Angle Scattering

X‐ray small‐angle scattering analysis of porous silicon layers

1989 ◽  
Vol 66 (2) ◽  
pp. 625-628 ◽  
Author(s):  
P. Goudeau ◽  
A. Naudon ◽  
G. Bomchil ◽  
R. Herino
Keyword(s):  
Porous Silicon ◽  
Small Angle ◽  
Small Angle Scattering ◽  
X Ray ◽  
Angle Scattering

Information retrieval from X-ray small-angle scattering with polychromatic (`white') synchrotron radiation

1983 ◽  
Vol 16 (1) ◽  
pp. 42-46 ◽  
Author(s):  
O. Glatter ◽  
P. Laggner
Keyword(s):  
Synchrotron Radiation ◽  
Small Angle ◽  
Particle Shape ◽  
Structural Information ◽  
Small Angle Scattering ◽  
Radius Of Gyration ◽  
X Ray ◽  
Angle Scattering ◽  
Slit Length ◽  
Hinge Bending

The possibilities of obtaining structural information from X-ray small-angle scattering experiments with `white' polychromatic synchrotron radiation using line collimation are investigated by numerical simulation. Theoretical scattering curves of geometrical models were smeared with the appropriate wavelength distributions and slit-length functions, afflicted by statistical noise, and then evaluated by identical methods as normally used for experimental data, as described previously [program ITP; Glatter (1977). J. Appl. Cryst. 10, 415–421]. It is shown that even for a wavelength distribution of 50% half width, the information content is not limited to the parameters derived from the central part of the scattering curves, i.e. the radius of gyration and the zero-angle intensity, but also allows qualitative information on particle shape via the distance distribution function p(r). By a `hinge-bending model' consisting of two cylinders linked together at different angles it is demonstrated that changes in the radius of gyration amounting to less than 5% can be detected and quantified, and the qualitative changes in particle shape be reproduced.

The Lipid Bilayer Structure of the Abnormal Human Plasma Lipoprotein X. An X-Ray Small-Angle-Scattering Study

1977 ◽  
Vol 77 (1) ◽  
pp. 165-171 ◽  
Author(s):  
Peter LAGGNER ◽  
Otto GLATTER ◽  
Karl MULLER ◽  
Otto KRATKY ◽  
Gerhard KOSTNER ◽  
...  
Keyword(s):  
Human Plasma ◽  
Lipid Bilayer ◽  
Small Angle ◽  
Small Angle Scattering ◽  
Plasma Lipoprotein ◽  
Bilayer Structure ◽  
X Ray ◽  
Angle Scattering ◽  
Scattering Study
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