Patent ID: 8742147

Claim:
A process for improving the selectivity of an ethylene epoxidation process employed in a reactor, said process comprising: (a) contacting an epoxidation catalyst comprising silver and rhenium with a feed comprising ethylene, oxygen, and an organic chloride for a period of time T 1 sufficient to produce at least 0.1 kilotons of ethylene oxide per cubic meter of epoxidation catalyst; (b) subsequent to step (a) and over a period of time T 2 , (i) reducing the quantity of organic chloride added to the feed by at least 25% and (ii) adding a saturated hydrocarbon co-moderator to the feed in an amount of at least 0.1 to 4 mole-%, based on the feed; and (c) subsequent to step (b), increasing the quantity of organic chloride added to the feed and terminating the addition of the saturated hydrocarbon co-moderator to the feed.