PUMICE-SUPPORTED PD-PT BIMETALLIC CATALYSTS - SYNTHESIS, STRUCTURAL CHARACTERIZATION, AND LIQUID-PHASE HYDROGENATION OF 1,3-CYCLOOCTADIENE

A series of pumice-supported palladium-platinum bimetallic catalysts w ere prepared and investigated by X-ray scattering (WAXS and SAXS) and XPS techniques. An alloy Pd-Pt was formed. The less abundant metal was found to segregate to the surface. The catalysts were tested in the l iquid-phase hydrogenation of 1,3-cyclooctadiene to cyclooctene, and co mpared with similarly prepared pumice-supported palladium and platinum catalysts and other supported Pd-Pt catalysts reported in the literat ure. The addition of platinum reduces the activity and the selectivity of the palladium catalysts. Differences between the activity of these pumice-supported catalysts and the activity of previously described P d and Pd-Pt catalysts on other supports, are attributed to the presenc e, in the latter, of diffusional processes. (C) 1995 Academic Press, I nc.