Pt L-III-edge XANES and EXAFS studies on gamma-Al2O3 supported Pt catalysts

Pt L-M-edge XANES and EXAFS were employed to investigate the nature of Pt/gamma-Al2O3, Pt-Sn/gamma-Al2O3 and Pt-Fe/gamma-Al2O3 catalysts. The results indicated that Pt species on these catalysts were all in the oxidized states before reduction, and in the metallic states after reduction. The dispersity of the Pt species on the catalysts was very high after reduction. The electronic properties of the highly dispersed Pt species were different from that of the bulk Pt in large crystallites. An interaction between Pt and the metal-oxide modified gamma-Al2O3 support is proposed. The interaction improved the dispersity of the Pt species on the catalysts and is thought to be the reason for the enhanced activity and selectivity for dehydrogenation reactions over these catalysts