Amino-functionalized KAUST-7 embedded polymers of intrinsic microporosity membrane with enhanced selectivity for CO2/CH4 separation

Rational design and construction of fillers and polymers are crucial for the development of high-performance mixed matrix membranes (MMMs). In this work, amino-functionalized metal-organic frameworks KAUST-7 (KAUST-7-NH 2 ) with square-shaped sheet morphology were utilized as fillers to fabricate MMMs by physical blending with the polymer of intrinsic microporosity (PIM-1). The square-shaped KAUST-7-NH 2 sheets, prepared via in situ replacement of 2-aminopyrazine into the KAUST-7 framework, exhibited superior separation performance compared to the mono-ligand KAUST-7. Benefiting from the strong CO 2 affinity, high porosity and optimal pore sizes of KAUST-7-NH 2 , the outstanding CO 2 /CH 4 separation performance of the composite membrane was observed. The integration of square-shaped KAUST-7-NH 2 sheets provides a 2.5-fold improvement in CO 2 /CH 4 selectivity together with acceptable gas permeability as compared to the original PIM-1 membrane. Furthermore, a 100-h continuous permeation test validated the stability of the fabricated MMMs. Remarkably, the resulting MMM retained 92% of their initial CO 2 permeability after 150 days (drop of only 249 Barrer), indicating that the reduction in CO 2 permeability was approximately 10-fold lower than that of the pristine PIM-1 membrane. The prepared MMMs exhibit enhanced CO 2 /CH 4 selectivity and long-term stability, making it a highly promising candidate for practical application.