Aromatic co-polyimide gas separation membranes derived from 6fda-dam-type homo-polyimides

A method for making a membrane for separating components of a sour natural gas feed, the method comprising the steps of:

• combining at least three different monomers to form a co-polyimide, the monomers including 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA);
• 2,4,6-trimethyl-m-phenylenediamine (DAM);
• and at least one component selected from the group consisting of:
• 4,4′-(hexafluoroisopropylidene)dianiline (6FpDA);
• 9,9-bis(4-aminophenyl) fluorene (CARDO);
• 2,3,5,6-tetramethyl-1,4-phenylenediamine (durene diamine);
• 2,2′-bis(trifluoromethyl)benzidine (ABL-21);
• 3,3′-dihydroxybenzidine;
• and 3,3′-(hexafluoroisopropylidene)dianiline;
• and
• preparing a dense film from the co-polyimide using a solution casting process.

A membrane for separating the components of a sour natural gas feed, the membrane comprising:

• at least three distinct moieties polymerized together, the moieties including a dianhydride selected from the group consisting of:
• a 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) based moiety;
• a benzophenone-3,3′, 4,4′-tetracarboxylic dianhydride (BTDA) based moiety;
• and a pyromellitic dianhydride (PMDA) based moiety;
• a 2,4,6-trimethyl-m-phenylenediamine (DAM) based moiety;
• and
• at least one component selected from the group consisting of:
• a 4,4′-(hexafluoroisopropylidene)dianiline (6FpDA) based moiety;
• a 9,9-bis(4-aminophenyl) fluorene (CARDO) based moiety;
• a 2,3,5,6-tetramethyl-1,4-phenylenediamine (durene diamine) based moiety;
• a 2,2′-bis(trifluoromethyl)benzidine (ABL-21) based moiety;
• a 3,3′-dihydroxybenzidine based moiety;
• and a 3,3′-(hexafluoroisopropylidene)dianiline based moiety.