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

Abstract

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.