US6932859B2
University of Texas System
1. A hollow fiber polymer membrane, comprising: a crosslinked polyimide polymer having covalent ester crosslinks; and having a CO 2 permeance of at least 20 GPU and a CO 2 /CH 4 selectivity of greater than 20, at 35 degrees C. and a pressure of 100 psia. 2. The hollow fiber polymer membrane of claim 1