Mixed matrix membranes incorporating bromine functionalized UiO-66 in the Tro<spacing diaeresis>ger's base polymer for enhanced CO2 capture

Membrane separation technology holds great potential for CO2 capture and H2 separation due to its simplified process, low energy consumption, and environmental benefits. Consequently, there is a pressing demand for membranes with ultra-high gas separation performance that can surpass the Robeson upper bound. To address this challenge, mixed matrix membranes (MMMs) were designed by combining rigid bridging ring polymerTro<spacing diaeresis>ger's base (TB) polymer with UiO-66 or UiO-66-Br to enhance gas separation properties of membranes. DFT calculations reveal that the interaction energy between UiO-66-Br ligands and TB is significantly lower than that of UiO-66 ligands with TB, suggesting the stronger interaction between the UiO-66-Br and TB polymer. The addition of UiO-66-Br enhances gas separation performance by providing additional gas transport pathways and increasing molecular sieving through its optimized pore size and functional groups. As a result, MMMs with a 40.0 wt% MOF loading exhibit CO2 and H2 permeabilities of 764.4 and 1127.8 Barrer, respectively, along with CO2/CH4, CO2/N2, H2/CH4, and H2/N2 selectivities of 15.6, 19.1, 23.0, and 28.2, surpassing the 2008 Robeson upper bound. Compared to TB membranes, the permeability of H2 and CO2 in the MMMs increased by over 247% and 222%, demonstrating exceptional gas separation performance. The design approach in this study offers an effective pathway for fabricating MMMs with high gas separation performance for efficient CO2 capture and H2 separation.