PT CLUSTERS IN BAKL ZEOLITE - CHARACTERIZATION BY TRANSMISSION ELECTRON-MICROSCOPY, HYDROGEN CHEMISORPTION, AND X-RAY ABSORPTION-SPECTROSCOPY

Platinum supported on BaKL zeolite was characterized by Transmission Electron Microscopy (TEM), hydrogen chemisorption, and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy. The results of all three techniques indicate the presence of highly dispersed platinum in the zeolite pores. There is no evidence of platinum outside the zeolite pores. The EXAFS data determine a Pt-Pt coordination number of 3.7, suggesting that the average platinum cluster in the zeolite consists of 5 or 6 atoms, consistent with the TEM and chemisorption data. The EXAFS data also provide evidence of the platinum-zeolite interface, indicated by Pt-O contributions at 2.14 and 2.70 Å, and a Pt-Ba contribution at 3.8 Å. The Pt/BaKL zeolite is one of the most highly dispersed supported platinum samples and one of the most structurally uniform supported metal catalysts. © 1990 J.C. Baltzer A.G. Scientific Publishing Company.