Novel mixed matrix membranes with indium-based 2D and 3D MOFs as fillers and polysulfone for CO2/CH4 mixed gas separation

Abstract

To address the limitations of polymeric membranes, mixed matrix membranes for CO₂ separation from biogas mixtures (CO₂ and CH₄) have been investigated utilizing various fillers. In this study, we investigated novel MMMs using 3D and 2D indium-based MOFs, MIL-68(In)–NH₂ and In(aip)₂, in a polysulfone polymer matrix. To confirm synthesis, both fillers were subjected to XRD and FTIR analysis, as well as FESEM characterization to assess their 2D and 3D structures. BET analysis revealed the pore size of MOFs. MMMs were characterized using XRD, FTIR, FESEM, and DSC to determine various membrane characteristics. MMMs were tested with CO₂ : CH₄ of 60 : 40 vol% to mimic the biogas mixture, and the CO₂ permeability of 144 Barrer and 79.2 Barrer was obtained for 20 wt% In(aip)₂/PSF membrane and 15 wt% MIL-68(In)–NH₂/PSF membrane. The highest CO₂/CH₄ selectivities of 19.8 and 24.4 were obtained for 15 wt% MIL-68(In)–NH₂/PSF MMM and 10 wt% In(aip)₂/PSF MMM, respectively. The gas permeation findings of this study were compared with existing literature and long-term stability analysis was done to assess the performance of membranes for commercial standards.