Enhancing CO2/N2 and CO2/CH4 separation in mixed matrix membrane: A comprehensive study on Pebax®1657 with SSMMP/IL for improved efficiency

Abstract Mixed matrix membranes (MMMs) have been proposed as a solution to surmount Robeson's trade‐off curves and have demonstrated efficacy in gas separation processes, particularly for CO 2 capture. In this study, MMMs based on Pebax®1657 were obtained utilizing synthetic silico‐metallic mineral particles (SSMMP) functionalized with ionic liquids (ILs). The objective was to attain enhanced CO 2 separation performance, thereby showcasing the potential to mitigate the environmental repercussions of industrial processes that entail greenhouse gas emissions. For membrane production, an ethanol/water mixture was used as solvent, with the SSMMP/IL content varying from 0.5 to 20% by weight of the polymer. The primary aim of this study was to assess the effect of filler addition on permeability and selectivity for CO 2 , CH 4 , and N 2 . Comprehensive analyses, including SEM, FTIR, TGA, DSC, and DMA were conducted to evaluate the properties of the produced membranes. Gas permeability and ideal selectivity were measured at 25°C and different pressures, ranging from 1 to 7 bar. Characterization results demonstrate that the glass transition temperature (Tg) of MMMs increased compared to pure Pebax®1657, indicating that the addition of SSMMP/IL reduces the flexibility of the PEO chains, forming a rigid interface at the polymer/filler, which may enhance selectivity. This effect, corroborated by gas permeation, was observed for both CO 2 /N 2 and CO 2 /CH 4 . For CO 2 /N 2 , the highest selectivity was achieved at lower filler concentrations, gradually decreasing as the filler load increased. MMM‐0.5 wt% achieved the highest selectivity of 91.96. The membrane CO 2 permeability rose with an elevated filler content, rising from 84.21 for pure Pebax®1657 to 192.17 Barrer for MMM‐20 wt% at 4 bar. The permeability results were influenced by the gas diffusion coefficients of the MMMs, which increased with increasing SSMMP/IL content. The effect of feed pressure on MMM‐5 wt% was also assessed, revealing that CO 2 permeability increased with increasing pressure, from 126.72 Barrer at 1 bar to 165.56 Barrer at 7 bar. This work showcased the viability of MMMs incorporating SSMMP/IL for industrial use, as they displayed separation capabilities that exceeded the 2008 Robeson upper bound. Highlights Mixed matrix membranes based on Pebax®1657 and SSMMP‐20%‐[bmim][Tf2N] were prepared. CO 2 permeability of the MMMs was increased by 128% and CO 2 /N 2 selectivity by 83%. Higher CO 2 pressures increase MMMs permeability. The obtained MMMs have separation performances above the Robeson upper Bound.