Development of an ion gel-based CO 2 separation membrane composed of Pebax 1657 and a CO 2 -philic ionic liquid.

A tough ion gel membrane containing a CO 2 -philic ionic liquid, 1-ethyl-3-methylimidazolium tricyanomethanide ([Emim][C(CN) 3 ]), was developed, and its CO 2 permeation properties were evaluated under humid conditions at elevated temperatures. Pebax 1657, which is a diblock copolymer composed of a polyamide block and a polyethylene oxide block, was used as the gel network of the ion gel membrane to prepare a tough ion gel with good ionic liquid-holding properties. The polyamide block formed a semicrystalline structure in [Emim][C(CN) 3 ] to toughen the ion gel membrane via an energy dissipation mechanism. The polyethylene oxide block exhibited good compatibility with [Emim][C(CN) 3 ] and contributed to the retention of the ionic liquid in the ion gel. The developed ion gel membrane showed a good CO 2 separation performance of 1677 barrer CO 2 permeability and 37 CO 2 /N 2 permselectivity under humid conditions of 75% relative humidity at an elevated temperature of 50 °C, which corresponds to an exhaust gas from a coal-fired power plant.