A novel optimized mixed-matrix membrane (MMM) of Pebax/polyethersulfone filled with ZIF-8 nanoparticles was fabricated and investigated for pure CO₂, CH₄, and N₂ gases and CO₂/CH₄ binary gas mixtures. The MMM offered higher permeability and selectivity in comparison with the neat membrane and exceeded Robeson's upper bound.

Abstract

Synthesized ZIF-8 (zeolitic imidazolate framework-8) nanoparticles were embedded in Pebax®1657/polyethersulfone (PES) to construct a mixed-matrix membrane. The membrane was characterized by scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, and tensile tests. The separation performance of CO₂ from CH₄ and N₂ was also measured at feed pressures of 4, 8, and 12 bar at room temperature. The results indicated that adding nanoparticles and glassy polymer into the Pebax®1657 matrix led to improved thermal and mechanical stabilities of the membrane and an 88 % increase in CO₂ permeance (at 30 wt % ZIF-8 in Pebax®1657/PES-10 %). The Pebax®1657/PES/ZIF-8 membrane exceeded Robeson's trade-off upper bound.