AgBF4/[emim][BF4] supported ionic liquid membrane for carbon monoxide/nitrogen separation

In this paper, AgBF 4 /[emim][BF 4 ] supported ionic liquid membranes (SILMs) were prepared successfully for CO/N 2 separation using nitrogen pressure immobilization procedures. The incorporation of AgBF 4 could decrease membrane weight loss, improve the pressure-resistant ability, and keep the critical pressure (0.45 MPa) of the SILMs. The high viscosity and undissolved AgBF 4 solids in membrane liquid would disturb gas molecular transport through membrane and give rise to the gas transport resistance. Therefore, the gas permeability decreased remarkably with increasing AgBF 4 carrier content in the membrane. When the molar ratio of AgBF 4 to [emim][BF 4 ] increased from 0:1 to 0.3:1, the CO/N 2 selectivity of the SILMs showed a great increase from ∼1 to ∼9 at 20 °C and 0.4 MPa, suggesting that AgBF 4 was an effective carrier for CO facilitated transport. The permeabilities of N 2 and CO increased at higher transmembrane pressure, indicating that molecular transport would dominate the transport process at high pressure. The temperature-dependent gas permeability followed the Arrhenius equation. Moreover, the differences between the activation energies of CO and N 2 became larger after introducing AgBF 4 , resulting in more obvious decrease in the CO/N 2 selectivity at higher operating temperature.