Factors Influencing Deactivation of Cs-Promoted, alpha-Alumina-Supported Silver Ethylene-Epoxidation Catalysts

摘要

The various factors relating to deactivation of an alpha-alumina supported, Cs-promoted, Ag ethylene epoxidation catalyst has bee examined before and after aging in a Bertz reactor using scanning electron microscopy (SEM) X-ary photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and electron energy loss spectroscopy (ELS). The SEM micrographs indicate that hte fresh catalysts consits of a fairly uniform coating of Ag over the alumina and sintering occurs during aging, The ELS data indicate that the Ag is in metallic form before and after aging while angle-reosved AES data indicate that the near-surface region of the Ag becomes enriched in oxygen during aging. The Cl content at the surfce also increases during aging dur to adsorption of the moderator.