IL-modified MOF-177 filler boosts the CO2/N2 selectivity of Pebax membrane

Abstract

Mixed matrix membranes (MMMs) having ionic liquid (IL) modified metal-organic frameworks (MOF) as fillers present a broad potential for enhancing the separation properties of the polymers. Here, we incorporated an IL, 1butyl-1-methyl-pyrrolidinium tricyanomethanide [BMPyr][TCM], into MOF-177 and used the corresponding composite as filler in Pebax polymer to fabricate IL/MOF-177/Pebax MMMs at different filler loadings. These MMMs along with those prepared by using pristine MOF-177 as a filler were then tested for CO2/N2 separation by measuring their CO2 and N2 permeabilities at 35 degrees C and 1 bar. The [BMPyr][TCM]/MOF-177/Pebax MMM having 10 wt.% filler loading showed remarkable improvements in both CO2 permeability (137 f 2.0 Barrer) and CO2/N2 selectivity (622 f 105) compared to the neat Pebax membrane having corresponding performance values of 98.0 f 2.0 Barrer and 64.5 f 6.0, respectively. This simultaneous improvement in both CO2 permeability and CO2/N2 selectivity breaks the trade-off limitation of polymer membranes. Besides, the MMMs having 10 and 15 wt.% loadings of fillers were located well above the updated Robeson's upper bound, demonstrating the great promise of [BMPyr][TCM]/MOF-177/Pebax MMMs for CO2/N2 separation.