Pd-Clusters on Carbon: Structure of Adsorbed PDCL2 Clusters and Interaction with Matrix
6th European Powder Diffraction Conference
22-25 Aug 1998
||European Powder Diffraction: Proceedings of the Sixth European Conference on Powder Diffraction EPDIC 6
1232 c. ISBN 978-0-87849-847-5.
Materials Science Forum
, E-ISSN: 1662-9752
Boreskov Institute of Catalysis SB RAS
In the present work we have tried to study by XRD RED (radial electronic density distribution) technique the structure of PdCh adsorbed on a carbon support. Our investigation shown that carbon black has a quasi-graphitic structure. The particles consist of hexagonal carbon networks, but only a quarter of them are formed by crystallites of a graphite type i.e. have three dimensional order.
Most of the networks are disoriented and deformed. The diffraction pattern of the PdCh/C has no peaks of Pd(II) compounds that may be explaned by their high dispersity. The differential RED curve of the sample has a set of peaks which may be referred to a-PdCh structure. The analysis of peak areas on the RED curve showed that about 60% of supported PdCh is in the form of clusters (<18A in size) with such structure. It is also observed Pd-C distances. Such distances appears because the PdCh molecule is oriented at the edge of a network so that the palladium atoms occupy the site which would be occupied by the carbon in a discontinuous network. This is due to similar interatomic distances in the carbon black and PdCh structures.