Functionalized ZIF-7/Pebax® 2533 mixed matrix membranes for CO2/N2 separation

Abstract

Membrane-based separation technology has evolved as a competitive approach for CO 2 capture from flue gas (mainly N 2 ). To achieve high separation performance, three partially NH 2 -, OH- and CH 3 OH- functionalized mixed-linker-ZIF-7 were successfully synthesized, and incorporated into polyether-block-amide (Pebax® 2533) polymer to form mixed-matrix membranes (MMMs). As evidenced by the CO 2 adsorption isotherms, introducing functional groups in the ZIF-7 framework was indeed beneficial for CO 2 adsorption. All MMMs composed of ZIF-7-NH 2 , ZIF-7-OH and ZIF-7-CH 3 OH offered better CO 2 /N 2 separation performance than the parent ZIF-7-Pebax® 2533 membrane, suggesting the positive effect of functionalized ZIF-7 fillers on the gas separation performance. Among the three functionalized ZIF-7 based MMMs, the ZIF-7-OH-Pebax MMMs exhibited the best performance for CO 2 /N 2 separation, which might be ascribed to the highest adsorption selectivity of CO 2 over N 2 predicted by ideal adsorbed solution theory (IAST) for ZIF-7-OH fillers. The 14% ZIF-7-OH-Pebax MMM showed high CO 2 permeability of 273 Barrer and CO 2 /N 2 separation factor of 38, which increased by 60% and 145% as compared with the neat Pebax membrane. The strategy of preparing functionalized MOFs with strong affinity for CO 2 provides an effective method to develop MMMs for highly efficient CO 2 separation. • Partially NH 2 -, OH- and CH 3 OH- functionalized mixed-linker-ZIF-7 were synthesized. • ZIF-7-OH exhibited highest adsorption selectivity of CO 2 over N 2 predicted by IAST. • Improved CO 2 permeability and CO 2 /N 2 selectivity of mixed-linker ZIF-7/Pebax MMM. • The ZIF-7-OH-Pebax MMMs exhibited the best performance for CO 2 /N 2 separation.