An investigation on gas transport properties of Elvaloy4170/ [Emim][Tf2N] hybrid membranes for efficient CO2/CH4 separation

This study investigates separation performance of a polymer-IL hybrid membrane comprised of Elvaloy4170 and 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][Tf2N]) ionic liquid. The goal is to incorporate superior features of Elvaloy4170 as a cost-effective commercial polymer with desirable CO2 permeability and mechanical strength, with those of [Emim][Tf2N] such as high affinity to CO2 molecules for fabricating high performance hybrid membranes. Results revealed that the presence of IL within the polymeric matrix leads to simultaneous enhancement of permeability and selectivity values. This is confirmed by the increase in CO2 permeability from 88 to 141 Barrer accompanied with 2.5 fold increase in CO2/CH4 ideal selectivity in hybrid membrane containing 40 wt. % IL. Both SEM-EDX analysis and Maxwell predictions confirmed the heterogeneous structure of polymer/IL hybrid membranes with no specific chemical interactions confirmed by FTIR-ATR spectra. The hybrid membranes prepared in this study showed promising separation performance at low temperature levels, e.g. CO2/CH4 ideal selectivity reached to 24.3 at 15℃. Moreover, separation performance of the hybrid membranes displayed minute variation facing higher pressures of up to 16 bar.