CHEMISORPTION OF ETHYLENE ONTO SUPPORTED PT/GAMMA-AL2O3 AND AG/GAMMA-AL2O3 AS FOLLOWED BY SOLID-STATE STATIC AND CP/MAS C-13 AND STATIC H-2 NMR-SPECTROSCOPY

The adsorption of ethylene onto two metal-supported catalyst systems is reported. The first is Pt on gamma-Al2O3. Here is it found that high-resolution solid-state C-13 CP/MAS methods cannot be utilized to investigate the structure of the adsorbed species. This arises due to the near ferromagnetic character of platinum metal. However, this problem can be circumvented by examining the solid-state H-2 NMR. From this investigations, it is clear that the dominant species on the surface is ethylidyne. These results are discussed in light of the previous work in the area. Ethylene adsorption was also examined for a supported silver system. In this system there are no problems with susceptibility of the metal surface. By utilizing a combination of mono- and dilabeled C-13 ethylene, the shielding tensor and the carbon-carbon bond distance of the adsorbed ethylene were deduced.