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 membranes for CO 2 /N 2 separation. Gas permeation testing revealed that these functionalized porous fillers substantially improved the CO 2 separation performance. Moreover, optimizing both the functionality and pore structure of the porous fillers was found to drastically improve the CO 2 /N 2 separation performance. In particular, the addition of 10 wt% PBP-menm (menm = 1,2-methylethylenediamine) induced an ultrahigh CO 2 permeability of 2988 barrers (158% higher than that of a pure polymer membrane), thus realizing excellent performance that surpasses the Robeson upper bound for CO 2 /N 2 separation. • Porous organic polymers possessing various functional groups were synthesized. • Defect-free mixed-matrix membranes comprising these functionalized porous fillers were successfully fabricated. • Optimizing both functionality and pore structure of porous fillers led to enhanced CO 2 transport. • The performance of the membrane with the optimum filler surpassed the Robeson upper bound for CO 2 /N 2 separation.