Ionic liquid‐polymeric membranes for CO2 separation: A new perspective on membrane integrity under pressure

Abstract

Membrane‐based CO2 separation is a promising technology compared to traditional processes, presenting advantages such as superior energy efficiency and reduced operational costs. This study investigates the enhancement of CO₂/N₂ separation performance by incorporating ionic liquid [hmim][Tf₂N] into polysulfone membranes. The membranes were produced with 5, 10, and 20 wt% IL, and their permeability was measured at 25°C under pressures of 1 and 4 bar. Stability tests were also conducted. At 1 bar, the membrane with 20 wt% IL exhibited the highest CO₂ permeability of 342.27 Barrer, while the membrane with 5 wt% IL demonstrated the best ideal selectivity for CO₂/N₂ of 27.87. At 4 bar, the membrane with 5 wt% IL showed the highest ideal selectivity for CO₂/N₂ of 40.81, with a CO₂ permeability of 144.26 Barrer. Leaching tests indicated potential integrity loss in ionic liquid composite polymer membranes at high pressures. Specifically, the CO₂ permeability of the PSF‐[hmim][Tf₂N] 5 wt% membrane increased continuously post‐testing due to IL leaching. However, the performance of the membranes remained stable at lower pressures (1 bar). These findings suggest that the produced membranes achieve higher permeability, CO₂/N₂ selectivity, and CO₂ diffusivity, making them suitable for post‐combustion gas separation applications.