Aminated amorphous carbon-enhanced PIM-based membranes for high-performance CO2/N2 separation with improved aging resistance

Efficient membrane-based carbon capture is a key front-end technology for achieving carbon neutrality. Crystalline carbon materials offer advantages such as high mechanical strength and a high degree of structural regularity, and are often used as fillers in the fabrication of mixed matrix membranes (MMMs). However, they tend to undergo π–π stacking and aggregation, leading to the formation of non-selective defects within the membrane. In this work, amorphous carbon material Ketjen black (KB) was deeply aminated via a diazonium-induced anchoring process (DIAP) and employed as a nanofiller to fabricate CO 2 -philic and aging-resistant PIM-based MMMs. TEM characterization confirmed that amino groups were successfully grafted onto both the surface and the internal pores of KB. Experimental results and molecular dynamics simulations revealed that the introduced amino groups enhanced the interaction energy between the filler and the polymer chains, thereby improving the compatibility between the inorganic and organic phases and significantly boosting the membrane's aging resistance. Additionally, the amino groups served as CO 2 -affinitive sites, effectively increasing the CO 2 /N 2 selectivity. The incorporation of uniformly sized amorphous carbon nanoparticles increased the fractional free volume of the membrane without introducing non-selective defects, thus improving the CO 2 permeability. Under optimized conditions, the resulting MMM exhibited a CO 2 permeability of 9024 Barrer and a CO 2 /N 2 selectivity of 23.7, exceeding the Robeson upper bound. After 180 days of aging, the CO 2 permeability decreased by only 16.9 %, demonstrating excellent long-term performance and offering a new paradigm for the application of amorphous carbon materials in PIM-based membranes for carbon capture.