Bulk Structure of Catalysts

In HRTEM, very thin samples can be treated as weak-phase objects (WPOs) whereby the image intensity can be correlated with the projected electrostatic potential of crystals, leading to atomic structural information. Furthermore, the detection of electron-stimulated XRE in the electron microscope (energy dispersive X-ray spectroscopy, or EDX, discussed in the following sections) permits simultaneous determination of chemical compositions of catalysts to the sub-nanometer level. Both the surface and bulk structures of catalysts can be investigated. 

In addition to understanding the bulk structure of catalysts and the distribution of bulk nuclei at the surface, an appreciation of the number and nature of acid sites is also of key importance. A number of NMR techniques have been developed in order to probe both Lewis and Br0nsted acidity at surfaces, and extensive reviews on many of them have been produced by various authors [183, 195, 196]. 

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