(558aw) High Performance Cobalt-Based IL/PIM-1 Thin Film Composite Membrane for Air Separation

Air separation is an important process in producing oxygen-enriched air or nitrogen-enriched air, and it has found wide application in industrial combustion and food preservation. Compared with cryogenic distillation and pressure swing adsorption, membrane-based air separation has attracted substantial attention due its inherent advantages of low cost, energy conservation and simple maintenance. However, the development of air separation membranes is frequently challenged by the trade-off between permeability and selectivity due to the close molecule sizes of O₂ (0.346 nm) and N₂ (0.364 nm). Facilitated transport membrane containing O₂ carriers, which can selectively and reversibly react with O₂ and thus facilitate O₂ transport in membranes. Cobalt-based ionic liquid (Co-IL) is an efficient O₂ carrier and drawing much attention.¹

In this study, thin film composite (TFC) membranes were prepared using polymer of intrinsic microporosity (PIM-1)² as the matrix and Co-IL (Bmim₂Co(SCN)₄, Bmim₂CoCl₄, Bmim₂Co(NO₃)₄) as the carrier. The composite membranes were characterized by SEM, FTIR, XRD, and gas permeation properties. SEM images revealed uniform and thin films (<1 μm) were fabricated. The FTIR spectra indicated the interaction between Co-IL and PIM-1 is physical. Meanwhile, the membranes exhibited outstanding air separation performance. The addition of a certain amount of Co-IL can improve the gas permeance and O₂/N₂ selectivity. Meanwhile, decreasing the feed pressure can further enhance the separation performance. The composite membranes with 0.4 wt% Bmim₂Co(SCN)₄ showed a O₂ permeance of >420 GPU and O₂/N₂ selectivity of >6, respectively, making them attractive for air separation.

References

1. Matsuoka, A.; Kamio, E.; Mochida, T.; Matsuyama, H., Facilitated O₂ transport membrane containing Co(II)-salen complex-based ionic liquid as O₂ carrier. J Membrane Sci 2017, 541, 393-402.
2. Liang, C. Z.; Liu, J. T.; Lai, J. Y.; Chung, T. S., High-performance multiple-layer PIM composite hollow fiber membranes for gas separation. J Membrane Sci 2018, 563, 93-106.