Preparation of Polyimide/Ionic Liquid Hybrid Membrane for CO/CH Separation.

Imidazole ionic liquids (IL) have good affinity and good solubility for carbon dioxide (CO). Such ionic liquids, combined with polyimide membrane materials, can solve the problem that, today, CO is difficult to separate and recover. In this study, the ionic liquid (IL) of 1-ethyl-3-methylimidazolium tetrafluoroborate (IL), 1-pentyl-3-methylimidazolium tetrafluoroborate (IL), 1-octyl-3-methylimidazolium tetrafluoroborate (IL), and 1-dodecylimidazolium tetrafluoroborate (IL) with different contents were added to a polyimide matrix, and a series of polyimide membranes blended with ionic liquid were prepared using a high-speed mixer. The mechanical properties and gas separation permeability of the membranes were investigated. Among them, the selectivity of the PI/IL membrane for CO/CH was 180.55, which was 2.5 times higher than the PI membrane, and its CO permeability was 16.25 Barrer, which exceeded the Robeson curve in 2008; the separation performance of the membrane was the best in this work.