Enhancing CO2 Separation Properties of Poly(ether-block-amide) Mixed Matrix Membranes using Trimethylamine-Assisted Synthesized MOF-5 Nanoparticles and Poly(ethylene glycol)

This study aims to enhance the CO 2 separation properties of Pebax-1657-based mixed matrix membranes (MMMs) by synergistic effects of triethylamine-assisted synthesized MOF-5 nanoparticles and PEG additive. The MOF-5 nanoparticles were synthesized via the precipitation method and incorporated into Pebax-1657 and PEG/Pebax-1657 blend. Based on the gas permeation experiments, the MOF-5/Pebax MMMs showed a slight increase in CO 2 permeability and a decrease in N 2 permeability by loading MOF-5 filler. The best performance was observed at 6 wt.% MOF-5, achieving a CO 2 permeability of 84 Barrer (a 24% improvement) and a CO 2 /N 2 ideal selectivity of 96 (a 22% improvement). Ternary MMMs with 35 wt.% PEG-600 and 8 wt.% MOF-5 exhibited a CO 2 permeability of 92 Barrer (a 35% improvement) and a CO 2 /N 2 ideal selectivity of 180 (a 131% improvement). Both MMM S surpassed the Robeson upper bound-2008, highlighting their industrial potential. Moreover, the CO 2 permeability increased with operating pressure enhancement up to 8 bar, primarily due to its higher condensability and adsorption in MOFs. In contrast, the N 2 permeability increased up to 6 bar, but declined at higher pressures due to matrix compaction. MMMs resisted compaction better than pure Pebax, maintaining superior CO 2 permeability and selectivity. The M Index provided a dual assessment of permeability-selectivity enhancements and the Robeson upper bound. The optimal membrane (PPM8) demonstrated excellent CO 2 separation performance, with a M Index value ranging from 0.5 to 1.5. • Synergistic enhancement of CO 2 separation using MOF-5 nanoparticles and PEG-600 in Pebax-1657-based MMMs. • Optimal CO 2 permeability of 92 Barrer with a CO 2 /N 2 selectivity of 180 was achieved, surpassing the Robeson upper bound (2008). • Ternary MMMs demonstrated superior resistance to matrix compaction under pressure, retaining performance. • M-index analysis confirms dual improvements in permeability and selectivity, with optimal membrane (PPM8) showing values between 0.5–1.5.