Gas Research Institute

S Alexander Stern

Hiroyoshi Kawakami

Guangbin Zhou

Ajay Y Houde

A process for separating a first gas from a second gas, having the steps of: (1) contacting one side of a semi-permeable gas separation membrane with a feed gas mixture containing at least the first gas and the second gas, wherein the membrane divides a separation chamber into a high-pressure side into which the feed gas mixture is fed and a low-pressure side; (2) maintaining a pressure differential across the membrane under conditions such that the first gas in the feed gas mixture selectively permeates through the membrane from the high-pressure side to the low-pressure side of the membrane; (3) removing from the low-pressure side of the membrane permeated gas mixture which is enriched in the first gas and depleted in the second gas; and (4) removing from the high-pressure side of the membrane a gas mixture which is enriched in the second gas and depleted in the first gas. The membrane used is made, at least in part, of a thin discriminating layer of polyimide having the repeating formula ##STR1## wherein R is: ##STR2##

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Manlius, NY, United States of America

S Alexander Stern