Mechanochemical synthesized amino-functionalized ultramicroporous ZIF based mixed-matrix membranes for CO2 separation

Abstract

Mixed-matrix membranes (MMMs) have arisen as an energy-saving and efficient candidate for CO2 separation that can mitigate the greenhouse effect. However, challenges still remain in achieving good filler-polymer compatibility and high separation performance. Herein, a mechanochemistry method is proposed to synthesize an amine-functionalized ultramicroporous ZIF-62 (ZIF-UC-6) with good CO2 affinity. Amino functional groups and open metal sites are introduced into ZIF-UC-6, which significantly improve its CO2 adsorption capacity of ZIF-62. According to the ideal adsorption solution theory (IAST) calculation, the CO2/CH4 and CO2/N2 selectivity of ZIF-UC-6 is ∼80 and ∼140, respectively. Besides, when ZIF-UC-6 is incorporated into Pebax, hydrogen bonds can form between filler and polymer, which can increase the interfacial compatibility in the MMMs. The optimized membrane possesses a CO2 permeability of ∼560 barrer, together with high CO2/CH4 and CO2/N2 selectivity of 41.8 and 86.2, surpassing the corresponding upper bounds. Moreover, the prepared MMMs have good pressure resistance and long-term stability. This work demonstrates an effective route for developing MMMs with good interfacial compatibility and high CO2 separation performance for potential industrial applications.