Application of X-Ray Diffraction Techniques to Study Highly Dispersed Supported Metals
In practice, the most important case of highly dispersed metals on polycrystalline or quasi-crystalline substrates are supported catalysts. Of special interest are those with low metal loading (not exceeding few wt.%) and with small particle size of the metal phase (less than 100 Å). Their diffraction patterns are a superposition of a weak broad diffraction profile from the metal which is very often obscured by a predominant diffraction profile from the support. It is assumed that the contribution of the intensity from the metal-support interphase boundary to the total diffracted intensity is negligible. One of the objectives in catalyst studies is to follow structural changes induced into its active phase by the catalytic conditions. For the supported metal catalysts it means to observe changes which the diffraction profiles originating from the metal have undergone. The aim is then to obtain the diffraction profile originating from the metal phase alone which can be subsequently handled using conventional procedures of profile analysis (see e.g.1).
KeywordsMetal Phase Diffraction Profile Hydride Phase Support Palladium Catalyst Palladium Hydride
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