EXAFS AND CATALYTIC ACTIVITY OF AGPT BIMETALLIC CLUSTER SUPPORTED ON NAY ZEOLITE

Abstract

Platinum clusters with ca. 1 nm in size have been prepared as encaged in supercages of NaY zeolite by the reduction of platinum after ion exchange of Pt(NH3)42+ into NaY. A series of bimetallic AgPt/NaY samples with Ag/Pt atomic ratios of 0, 0.11, 0.43 and 1.0 have been obtained by the reduction of silver after subsequent ion exchange of Ag+ into the Pt/NaY sample. The result from measurements for Xe-129 NMR spectrum, and hydrogen chemisorption has indicated that the Ag atoms were put together onto the Pt cluster, with the surface enriched by Ag atoms. The extended X-ray absorption fine structure (EXAFS) of the bimetallic cluster measured above Pt L(III) and Ag K edges have been analyzed with reference EXAFS spectra which were experimentally obtained from the metal foils and those for AgPt pair which were theoretically prepared by FEFF codes distributed by Rehr et al. The catalytic activity in ethane hydrogenolysis over the AgPt bimetallic cluster has also been measured.