CATALIZZATORE PER LA PREPARAZIONE DI ETILENOSSIDO

摘要

Supported silver catalysts active for conversion of ethylene to ethylene oxide are prepared by coating the surface of catalyst support with an overlayer of a silver salt/polyacrylonitrile complex and then heating to about 200 DEG -600 DEG C to pyrolyze the polyacrylonitrile and convert the silver ions into discrete less than 150nm (nanometers) particles of silver. The silver salt/polyacrylonitrile complex overlayer is preferably prepared in situ by polymerization of a silver salt complexed acrylonitrile monomer on the surface of the support. Supported silver catalysts prepared by this process, when activated by treatment with a flowing stream containing a mixture of ethylene and oxygen in combination with an inert gas or by treatment with a flowing stream of air under conditions of time and temperature which facilitate removal of the excess carbon residue but avoid sintering of the catalyst particles, are highly active and selective in the conversion of ethylene to ethylene oxide.