Design and Performance Evaluation of Amino Acid-Decorated UiO-66-NH2/Pebax Mixed Matrix Membranes for Efficient CO2 Separation

To advance CO 2 separation technologies, lysine-decorated UiO-66-NH 2 (LYS-UiO-66-NH 2 ) fillers were synthesized via a lysine modification and integrated into a Pebax-1657 matrix, yielding high-performance mixed matrix membranes. The carboxyl groups of the amino acids provide nucleophilic sites, promoting stronger interactions between LYS-UiO-66-NH 2 and CO 2 molecules. Moreover, the N–H and C = O bonds present in LYS-UiO-66-NH 2 facilitate hydrogen bonding with complementary C = O and N–H functional groups in the Pebax polymer backbone. These interactions significantly improve filler–polymer compatibility, enhancing interfacial adhesion and achieving uniform filler dispersion within the membrane matrix. Characterizations conducted via Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and thermogravimetric analysis confirmed successful synthesis of the LYS-UiO-66-NH 2 filler particles, exhibiting high crystallinity, uniform distribution within the polymer matrix, superior thermal stability, and absence of discernible interfacial defects. Compared to pristine Pebax membranes, the LYS-UiO-66-NH 2 /Pebax MMM containing 3 wt% filler exhibited a CO 2 permeability of 104.62 Barrer and a CO 2 /N 2 selectivity of 85.75 at 30℃ and 0.1 MPa, corresponding to increases of 74.16% and 75.61%, respectively, thereby surpassing the 2008 Robeson upper bound. This work demonstrates the considerable potential of the designed MMMs for highly efficient CO 2 separation.