Enhancing CO2/(light gases) separation performance of Pebax-based mixed-matrix membranes by [BMIM][AC] ionic liquid

Abstract

Incorporating the proper additive with an affinity towards target gases is considered a helpful strategy for simultaneously improving membrane permeability and selectivity. In this research, the superior features of polyetherblockamide polymer (Pebax1657), 1–Butyl3–methylimidazolium acetate ([BMIM][AC]) ionic liquid (IL), and aluminum oxide (Al2O3) nanoparticles were blended to produce efficient ternary mixed-matrix membranes for CO2 removal from light gases. The fabricated membranes structures have been evaluated by FTIR3ATR, FESEM, XRD, and DSC analyses. The permeation rates of unmixed CH4, N2, and CO2 gases through the resulting membranes were obtained at 25 °C and a feed pressure range of 4–10 bar. The gas permeability results showed that embedding Al2O3 nanoparticles as the loading up to 6 wt% increased the CO2/(light gases) separation performance. Besides, adding the IL into the polymer matrix boosted the membranes gas separation efficiencies caused by the increased CO2 solubility and their fractional free volume. The results also revealed that the resulting membrane containing 15 wt% of [BMIM][AC] IL and 6 wt% of Al2O3 nanoparticles, which has the best gas separation efficiency, is the optimum ternary mixed-matrix membrane. The comparison between the optimized membrane and the unloaded one efficiencies demonstrated that CO2/N2 and CO2/CH4 selectivities, along with the CO2 permeability, rose from 63.40, 19.93, and 115.39 Barrer for the unloaded membrane to 81.18, 25.14, and 166.42 Barrer for the optimum membrane (around 28 %, 26 %, and 44 % increments), at 10 bar and 25 °C, respectively.