Enhanced CO2/CH4 Separation Performances of Mixed Matrix Membranes Incorporated with Two-Dimensional Ni-Based MOF Nanosheets

Blending porous inorganic fillers into polymers to fabricate mixed matrix membranes (MMMs) is an efficient method to acquire good-quality membranes for CO2 separation and purification. The poor interface coupling between bulky filling particles and polymer phase in MMMs results in reduced mechanical strengths with low separation performances. The novel two-dimensional (2D) and ultrathin α-Ni(im)2 nanosheets with high aspect ratios are herein synthesized and blended with Pebax MH 1657 to prepare MMMs. The larger contacting area and strong hydrogen bonding between α-Ni(im)2 nanosheets and Pebax improve their compatibility to form defect-free MMMs. The ultrathin α-Ni(im)2 nanosheets in MMMs can effectively enhance CO2/CH4 selectivity based on molecular sieving. With the addition of 2 wt % of α-Ni(im)2 nanosheets, the as-prepared MMMs exhibit CO2/CH4 selectivity up to 33.4 with a permeability of 100.6 Barrer. Compared with pure Pebax membrane, the separation selectivity shows a 72% increase with no significant change in CO2 permeability.