INVESTIGATION BY X-RAY ABSORPTION SPECTROSCOPY OF PLATINUM CLUSTERS SUPPORTED ON ZEOLITES

The onset of the Lm edge of the X-ray absorption spectrum of platinum in Y-zeolites invol-ves an electronic transition from core to band levels producing a so-called white line. The spec-tral area of this increases and the edge position shifts to higher energies, first when the platinum particle size becomes small enough so that the clusters are in the supercages, second when the clusters are covered with oxygen, and third when multivalent cations are introduced in the zeo-lite. Both features of the absorption edge indicate that under the three above circumstances, platinum becomes more electron deficient. This conclusion had been inferred earlier from the enhanced catalytic activity of Pt clusters in Y zeolites. © 1979, Walter de Gruyter. All rights reserved.