STUDY OF METAL CATALYSTS BY TEMPERATURE PROGRAMMED DESORPTION .I. CHEMISORPTION OF ETHYLENE ON SILICA-SUPPORTED PLATINUM

An attempt was made to extend the temperature programmed desorption (TPD) technique to the study of metal catalysts by investigating the chemisorption and surface reactions of ethylene on silica-supported platinum. Self-hydrogenation was observed at room temperature as an important part of the process. In addition, a large fraction of ethylene remained irreversibly adsorbed, undergoing farther self-hydrogenation at about 100 ° and decomposition to methane at around 220 ° as the temperature was raised during the subsequent TPD. A second decomposition, observed at temperatures higher than 500 °, is probably due to the formation of methane from the fragmental surface residue left after the first (lower temperature) decomposition. The temperature programmed desorption technique was applied in this instance not only to the simple desorption processes but also to the surface reactions which give desorbed material different from the initially chemisorbed species. © 1969.