Selective Post-combustion CO2 Capture Using MOF-integrated Nanofibrous Aerogels

Mitigating rising anthropogenic carbon dioxide emissions requires the development of efficient, low-energy intensive capture technologies. Metal-Organic Frameworks (MOFs) are highly promising due to their excellent CO2 adsorption capacities, high porosity, and structural tunability. However, their inherent powder form limits their practical application in industrial post-combustion gas separations due to mechanical instability and pressure drops in continuous flue gas columns. This project focuses on the synthesis and characterization of MOF-integrated aerogels using two prominent MOFs for CO2 capture: Calgary Framework-20 (CALF-20) and University of Texas at San Antonio-280 (UTSA-280). Ultralight, mechanically robust 3D nanofibrous aerogels (NFAs) were fabricated from cellulose diacetate (CDA) and silica via electrospinning, homogenization, and freeze-drying. Pre-synthesized MOFs were incorporated into the matrix, achieving MOF loadings up to 85 wt%. Morphological and structural characterization confirmed successful incorporation of MOF crystals within the polymeric fibers, preserving their intrinsic crystalline structures. Brunauer-Emmett-Teller analysis and static gas adsorption at 15, 25, and 35 °C confirmed the preservation of the intrinsic high internal surface areas and CO2 adsorption capacities of the pure MOFs within the composites. The composites exhibited high CO2/N2 selectivity in diluted flue gas conditions, verified by Ideal Adsorbed Solution Theory (IAST). Isosteric heat of adsorption calculations confirmed a physisorption mechanism, ensuring a low-energy requirement for regeneration. The materials demonstrated excellent cyclic stability, maintaining their initial capacity across ten consecutive adsorption-desorption cycles. Dynamic performance was validated through continuous-flow breakthrough experiments using a simulated flue gas mixture (3.5% CO2 / 96.5% N2).