Small-angle scattering, study catalysts

In addition to diffraction, one can perform small-angle scattering, where the scattering centers are the interfaces between particle and support, particle and gas phase, and support and gas phase. Examples can be found in the studies of Goodisman et al. [17] on supported catalysts, and of Beelen and colleagues on catalyst supports [18]. 

Silica gel cracking catalysts have also been studied. These materials are amorphous and yield no powder diagrams but they do give a very maiked small angle scatter. If the particle distributions obtained from small angle scatter are used to calculate surface areas and these areas are related to the activity, fairly reasonable correlations result. Certain complications concerning these relationships are introduced by various types of treatments applied to the catalysts and by the iron content of commercially deactivated samples. 

There are two very general X-ray techniques for study of the metal particle size distribution the line-broadening analysis (LBA) and the small angle X-ray scattering (SAXS) (lb, 170). Other methods include the radial electron distribution (RED) and the extended X-ray absorption fine structure (EXAFS), which are aimed primarily at studying the structure of catalysts (Section IV,G). 

Small angle. -ray scattering studies were also made on these catalysts and the usual measurements and analyses of the data were made. The results were plotted with the particle size as abscissa and the weight per cent of the particles of this particle size as ordinate and the datum points were connected by a line to yield the simulated distribution curve. (Jellinck, Solomon, and Fankuchen, 18). It is obvious that a wide range of particle... 

The state of the catalyst precursor was studied by commonly used methods of X-ray photoelectron spectroscopy (XPS), WAXS, small angle X-ray scattering (SAXS) and atomic radi distribution (RDF). 

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