Highly promoted CO2 separation of poly(ether-block-amide) based mixed matrix membranes using MOFs@aminoclay architectures as fillers

Abstract

Abstract In this research, a collection of new composites constructed from aminoclays (MgAC and ZrAC) and MOFs are inserted into the PEBAX matrix for gas separation inspections. In fabricated UiO-66-(COOH)2@CuBDC@MgAC and MIL-121@CuBDC@MgAC composites series, amine groups of MgAC, unoccupied Cu ions of CuBDC and free carboxylic acid in the pores of UiO-66-(COOH)2 and MIL-121 are intensely involved in superior CO2 permeability of prepared MMMs from these composites. Besides, the nanosheet formation of CuBDC MOF induced by MgAC sheets develops the interphase regions (MOF-MOF and PEBAX-composites) which are also responsible for such obtained CO2 permeability against N2. Additionally, lower pore diameter of CuBDC in comparison with UiO-66-(COOH)2 and MIL-121 can exert sieving effect for crowded gas molecules which pass through the UiO-66-(COOH)2 and MIL-121 layers. In these series, PEBAX/Zr@Cu@Mg-4 demonstrates CO2 permeability of 320.15 barrer and CO2/N2 selectivity of 147.27. A new aminoclay based on zirconium is synthesized and added to the constructed composites as the outer layer. The provided ZrAC@UiO-66-(COOH)2@CuBDC@MgAC and ZrAC@MIL-121@CuBDC@MgAC composites are also examined as fillers in PEBAX matrix. Apparently, the interphases of MMMs are gotten close to their ideal states by ZrAC sheets existence in composites and gas behavior of all MMMs are ameliorated compared to the last MMMs series. In this regard, PEBAX/Zr@Zr@Cu@Mg-4 exhibits CO2 permeability of 407.77 barrer and CO2/N2 selectivity of 87.46. The fabricated composites and membranes are identified by FT-IR, XRD, SEM and HRTEM. The membranes are also characterized by TGA, surface contact angle and Stress-Strain analysis.

Keywords

• Gas separation
• MOF
• Aminoclay
• PEBAX
• Mixed matrix membrane