Mixed Matrix CO₂ Separation Membranes based on Polysulfone with Cu-BTC Metal-Organic Framework and Poly(ethylene glycol)grafted-Carbon Nanotubes

Mixed matrix membranes (MMMs) are heterogeneous membranes comprised of inorganic fillers distributed in a polymer matrix, and have been receiving considerable attention in gas separation. The objective is to take advantage of the benefits provided by each phase that can include high selectivity and permeability due to the inorganic fillers, economical processability of the polymers, and enhanced mechanical properties. Yet, the advancement of MMMs is mostly challenged by the fabrication of defect-free membranes, the proper filler dispersion, and the selectivity/permeability trade-off. In this work, we have developed polysulfone (PSF) MMMs by exploring two different fillers, namely, Cu-BTC (HKUST-1) metal-organic framework and polyethylene glycol-grafted-carbon nanotubes (PEG-g-CNTs) via solvent casting. Following morphological and structural characterization of the developed PSF/HKUST-1 and PSF/PEG-g-CNTs membranes, their CO2 separation performance was evaluated in a gas permeation rig in terms of permeance and selectivity for three different gases, namely, CO2, CH4 and N2 at 2.5 bar and room temperature. Indicatively, an increase in CO2 permeance by 23% was obtained for the MMM containing 10 wt% of HKUST-1, while for the one loaded with 10 wt% of PEG-g-CNT, an increase in CO2 permeance by 35% was observed.