Effective functionalization of porous polymer fillers to enhance CO2/N2 separation performance of mixed-matrix membranes

Abstract

A series of porous organic polymers (denoted as PBP-x) possessing various functional groups was synthesized via Friedel-Crafts alkylation followed by post-synthetic functionalization using amine and sulfonic groups. These functionalized porous polymers were incorporated into an in-house polyimide to fabricate mixed-matrix mem-branes for CO2/N-2 separation. Gas permeation testing revealed that these functionalized porous fillers sub-stantially improved the CO2 separation performance. Moreover, optimizing both the functionality and pore structure of the porous fillers was found to drastically improve the CO2/N-2 separation performance. In particular, the addition of 10 wt% PBP-menm (menm = 1,2-methylethylenediamine) induced an ultrahigh CO2 permeability of 2988 barrers (158% higher than that of a pure polymer membrane), thus realizing excellent performance that surpasses the Robeson upper bound for CO2/N-2 separation.