UV-Cross-Linked Iongel/MOF Membranes for CO2 Separation

Abstract This study demonstrates the successful development of mixed matrix iongel membranes (MMIMs) incorporating high ionic liquid (IL) content and metal–organic framework (MOF) fillers to enhance CO2 separation performance. Three MOFs─Cu(BTC), MIL-53, and MOF-177─were incorporated into a UV-polymerized, solvent-free polyethylene glycol diacrylate (PEGDA-80) matrix. Dense and defect-free membranes were obtained and fully characterized in terms of morphology, chemical structure, hydrophilicity, mechanical properties, and thermal stability. The membranes exhibited thermal stability across a broad temperature range (298–473 K), although mechanical integrity decreased with MOF incorporation. Gas permeation experiments with pure gases (CO2, N2, CH4) revealed that MOF incorporation significantly enhanced CO2 transport, with Cu(BTC)-based MMIMs achieving the highest CO2 permeability (290 Barrer) and ideal selectivities (30.8 for CO2/N2 and 19.0 for CO2/CH4). Mixed-gas experiments under realistic flue-gas and biogas conditions (2 bar, 15–40 vol % CO2) further confirmed the superior performance of PEGDA-80 TFSI-10 Cu(BTC), including strong sensitivity to humidity: CO2 permeability increased from 216 to 412 Barrer at 11 vol % RH. The results demonstrate that combining high IL content with MOF fillers─particularly Cu(BTC)─is an effective strategy to produce thermally stable, defect-free iongel membranes with markedly improved CO2 separation performance.