Phenolic resin regulated interface of ZIF-8 based mixed matrix membrane for enhanced gas separation

Abstract

The performance of mixed matrix membranes (MMMs) is significantly determined by the inherent structure and composition of incorporated nanofillers. In this work, the core-shell ZIF-8@RF nanofillers were prepared through a kinetically-controlled growth of zeolitic imidazolate framework-8 (ZIF-8) and polymerization of resorcinol and formaldehyde (RF), followed by being incorporated into the glassy 6FDA-Durene and rubbery Pebax 1657 via a physical blending approach to form MMMs. Benefiting from the enhanced interfacial compatibility, CO2 affinity, and the intrinsic characteristics of porous ZIF-8, the resultant MMMs demonstrated outstanding performance for CO2/CH4 separation. The CO2 permeability and CO2/CH4 selectivity of the ZIF-8@RF/6FDA-Durene (ZIF-8@RF/Pebax 1657) MMMs increased up to 1332.1/363 Barrer and 28.6/29.6, corresponding to an improvement of 65.4/116.3% of the CO2 permeability and 49.7/53.4% of the CO2/CH4 selectivity compared to the pristine membrane. Meanwhile, CO2/CH4 selectivity of ZIF-8@RF MMMs increases by up to 33.0% and 28.1% in comparison to the ZIF-8 without RF layer MMMs, respectively. More importantly, both MMMs can maintain their extraordinary separation performance after stabilized in the existence of moisture. These results demonstrate that the separation performance of the MMMs was remarkably improved with the addition of ZIF-8@RF.