Process for improving the selectivity of an EO catalyst

摘要

The present invention relates to a process for improving the overall selectivity of an EO process for converting ethylene to ethylene oxide utilizing a highly selective EO silver catalyst containing a rhenium promoter wherein following normal operation a hard strip of the chloride on the surface of the catalyst is conducted in order to remove a portion of the chlorides on the surface of the catalyst. Following the hard strip, the catalyst is optionally re-optimized. Surprisingly, it has been found that the selectivity of the catalyst following the hard strip may be substantially higher than the selectivity prior to the hard strip.

主权项

1. 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 T1 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 T2,
(i) reducing the quantity of organic chloride added to the feed by at least 50% and(ii) increasing the reactor temperature by about 1 to 30° C.; and (c) subsequent to step (b), increasing the quantity of organic chloride added to the feed such that the quantity present in the feed is between 80 and 120% of the quantity that was present in the feed prior to step (b), and reducing the reactor temperature to within 5° C. of the prior reactor temperature.