CO2 separation performance for PIM based mixed matrix membranes embedded by superbase ionic liquids

Mixed matrix membranes (MMMs) have drawn much interest in CO2 separation due to their excellent separation performance, mechanical property, and desirable processability. However, obtaining highly compatible MMMs is a great challenge and is vital to avoid the loss of the separation selectivity of the MMMs. In this work, superbase ionic liquid (1,8-diazabicyclo[5,4,0]undec-7-ene imidazole ([FIDBU] [Im])) was used as a wetting agent to increase the interfacial compatibility between ZIF-67 and PIM-1, hence improving the membrane gas separation. [HDBU][Im] embeding into the MMMs could efficiently enhance the compatibility and diminish the interfacial voids. Furthermore, incorporating 5 wt% [HOBO] [Im]@ZIF-67 nanocomposite into the PIM-1 matrix improves the gas permeability and CO2 selectivity. The separation performances under the different temperatures were also conducted and showed that reducing temperature slightly decreases the gas permeability but significantly increases the CO2/CH4 selectivity via enhancing the CO2 solubility. The permeation active energies, diffusivities and solubilities were obtained to explain the gas permeate mechanism. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

This study used a superbase ionic liquid as a wetting agent to enhance the interfacial compatibility between ZIF-67 and PIM-1, improving the gas separation performance of the membrane. Incorporating a nanocomposite into the PIM-1 matrix also increased gas permeability and CO2 selectivity.