Ultra-High Selective Thermal Cross-Linked Membranes Fabricated via Tröger Base/Ionic Liquid Hybrid Precursors

Hydrogen (H2) is considered as one of the most promising energy carriers for the future, while to date H2 is still primarily produced as byproducts of various chemical processes. Efficient H2 separation from gas mixtures is crucial. In this study, thermal cross-linked membranes with ultrahigh selectivity were obtained by introducing ionic liquids (ILs) into Tröger base (TB) polymers. The resultant cross-linked membranes were thoroughly characterized using scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, and Fourier transform infrared analyses, all indicating the membrane was cross-linked at a relatively low temperature (300 °C). Furthermore, by optimization of the IL content, thermal cross-linking temperature, as well as cross-linking duration time, TB-5%[Emim][Tf2N]-300 °C-2 h membranes showed an approximately 28.9-fold and 11.7-fold increase in H2/N2 and H2/CH4 selectivity, respectively. At the same time, the H2 permeability was also increased from 9.23 to 31.69 Barrer. These results denoting the thermal cross-linking method can be effective in promoting the gas separation performances.