PIM-based mixed-matrix membranes containing MOF-801/ionic liquid nanocomposites for enhanced CO2 separation performance

Abstract

In this work, we fabricated PIM-based mixed matrix membranes (MMMs) containing MOF-801/ionic liquid nanocomposites to enhance CO2 separation performance of pure polymer membranes. All membranes and MOF-801/ionic liquid nanocomposites were prepared by solution casting method and wet impregnation, respectively. The samples were analyzed by SEM, XRD, FTIR, TGA and Nitrogen adsorption-desorption measurements. The nanocomposites are composed of metal-organic framework (MOF) MOF-801 and ionic liquid (IL) adsorption capacity. MOF-801 can well control the dispersion of IL in the polymer matrix, which is conducive to exposing more active sites in the nanocomposites to improve the CO2 adsorption selectivity of MOF-801/ionic liquid nanocomposites. At the same time, the porous structure of nanocomposites also enhances the gas adsorption and diffusion, thereby improving the gas separation performance. Compared with pure PIM-1 membranes, the CO2 permeability and CO2/N2 selectivity of IL@MOF/PIM-5% MMMs was increased by 129% and 45% (CO2 = 9420 Barrer, CO2/N2 = 29）, respectively. Compared with MOF-801/PIM-1 MMMs, the permeability of CO2 decreased slightly but the selectivity of CO2/N2 increased from 27 to 29. The aging test showed that the CO2 permeability of MMMs could remain above 70% after 90 days. The anti-plasticization performance of MMMs has also been significantly improved. The CO2 separation performance of IL@MOF/PIM-5% MMMs significantly exceeded the 2008 Robeson upper bound, showing excellent gas separation performance and working stability.