NAY ZEOLITE-SUPPORTED RE-PT CATALYSTS PREPARED FROM ORGANOMETALLIC PRECURSORS - EVIDENCE OF THE RE-PT INTERACTION FROM INFRARED AND X-RAY-ABSORPTION SPECTROSCOPIES

Model zeolite Y-supported Re-Pt catalysts were prepared from zeolite-s upported Pt that was prepared from platinum carbonyl clusters. [HRe(CO )5] was added to this zeolite, and the sample was treated in H-2 at di fferent temperatures. The samples were characterized by infrared and X -ray absorption spectroscopies. Re-Pt interactions were significant, a s indicated by (1) infrared and EXAFS spectra identified with Re subca rbonyls interacting with Pt clusters following treatment of the sample in H-2 at 185-degrees-C and (2) development of a cluster morphology w ith Re surrounding Pt clusters in the supercages and present in the Pt -zeolite interface. EXAFS data show that the first-shell Pt-Pt coordin ation number characterizing the sample treated in H-2 for 0.5 h at 285 -degrees-C was 8.2 when the sample contained no Re and was 5.1 when Re was present. Re significantly inhibits Pt cluster agglomeration durin g the treatment in H-2.