Enhanced CO2 Separation Performance of Matrimid 5218 Membrane by Incorporation of Poly(Arylene Ether Sulfone) Containing Phenylphosphine Oxide Group

This study aims to synthesize and characterize poly(arylene ether sulfone) containing phenylphosphine oxide (PESPPO) group and incorporate it into Matrimid 5218 at different loadings to fabricate membranes for CO₂ separation from CH₄ and N₂. Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and Differential Scanning Calorimetry (DSC) are employed to study the interactions between PESPPO and Matrimid 5218. Structural, morphological, and thermal analyses of the fabricated membranes reveal excellent miscibility, even at higher PESPPO loadings. The single-gas permeability results for CO₂, CH₄, and N₂ gases through the fabricated membranes demonstrate significant improvements in CO₂ separation from CH₄ and N₂ compared to the neat Matrimid 5218 membrane. The maximum CO₂ permeability is achieved at a 20 wt.% PESPPO loading. However, the highest CO₂/N₂ and CO₂/CH₄ selectivity is measured at 15 wt.% PESPPO loading. The optimized blend, comprising 15 wt.% PESPPO, exhibits a 2.36-times increase in CO₂ permeability, along with a 2.10-times and 1.92-times enhancement in CO₂/N₂ and CO₂/CH₄ selectivity, respectively, compared to the neat Matrimid 5218. Moreover, feed pressure variations minimally influence CO₂/N₂ and CO₂/CH₄ selectivity, and prolonged testing time does not noticeably affect CO₂ selectivity over N₂ and CH₄.