Supported metals, small particles reconstruction

In supported catalysts there is evidence that particle morphology is affected by the nature of the support, and by the methods of preparation and pretreatment. Coalescence and reconstruction of clean particles should be extremely rapid. The fact that in many cases small particles in contact do not combine into a single coherent particle suggests that the surface of supported metal particles may be relatively highly contaminated. When this occurs it must affect catalytic properties and correlations between activity and structure. 

The hydrogenolysis of EtaSiH over silica-supported Pd and Pt catalysts resulted in significant poisoning, specifically, the loss of activity in the hydrogenation of cyclohexene.375 Oxidation, however, fully restored the activity of catalysts with small metal particles (>50% dispersion) as a result of surface reconstruction. 

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