Nanoconfined CO2-philic ionic liquid in laminated g-C3N4 membrane for the highly efficient separation of CO2

Membrane separation technology has received widespread attention in the field of gas separation because of small footprint, convenient operation and low energy consumption. However, membranes separation are subject to a trade-off between permeance (or permeability) and selectivity. Herein, a novel kind of supported oinic liquid membrane (SILM) was constructed by nanoconfined 1-ethyl-3-methylimidazole acetate ([EMIm][AcO], IL) in the two-dimentional (2D) channels of the g-C3N4 laminated membrane for CO2/N2 and CO2/CH4 separation. Due to the nanoconfinement of ILs in 2D g-C3N4 laminated membrane and the appropriate nanofluidic channels constructed by the g-C3N4 nanosheets, the as-prepared g-C3N4 SILM possesses outstanding permeance and selectivity for CO2 in separation of CO2/N2 and CO2/CH4. The experimental result shows that g-C3N4 SILM possesses maximum CO2 permeance of 992.97 GPU in separation of CO2/N2 and 1160.52 GPU in separation of CO2/CH4 under 1 bar, 25℃. Meanwhile the resultant g-C3N4 SILM shows excellent selectivity for CO2/N2 (52.49) and CO2/CH4 (48.41) respectively. Moreover, the resulted g-C3N4 SILM displays excellent thermal stability and durability. After 60 h test, its separation performance has no obvious change. The findings of our study demonstrate that nanoconfined the IL into the 2D g-C3N4 is a novel strategy for the preparation of high-performance supported liquid membrane for the separation of CO2/N2 and CO2/CH4.