Constructing MOF-doped two-dimensional composite material ZIF-90@C3N4 mixed matrix membranes for CO2/N2 separation

Two-dimensional nanomaterials have the characteristics of high aspect ratio and high space utilization, which has huge potential advantages in gas separation. In this work, g-C 3 N 4 two-dimensional nanosheets with sieving pore structure were selected as templates and combined with ZIF-90 to construct a 0-dimensional/2-dimensional composite material ZIF-90@C 3 N 4 (ZCN). The complete two-dimensional g-C 3 N 4 nanosheets were stripped under acid etching conditions at 25 °C. ZIF-90 was distributed in an orderly manner on the two-dimensional nanosheets, and the nanosheets were spread out due to the growth of ZIF-90 to provide more free volume. The gas permeation experiment proved that the ZCN has a better CO 2 /N 2 separation performance. The ZCN/Pebax mixed matrix membrane (MMM) with the optimized 8.0 wt% ZCN loading showed an improved CO 2 permeability of 110.5 Barrer and a CO 2 /N 2 selectivity of 84.4, surpassing the Robeson upper bound (2008). The results demonstrated that the designed composite filler with 2D nanosheets is an effective strategy to enhance gas separation performance of MMMs and verified the application potential in gas purification industry.