Metal ionic liquid-based hybrid membranes for ammonia separation through moderate interaction sites and cooperative transport channels

The combination ionic liquids (ILs) with membranes is a potential method for direct NH 3 separation. In particular, ILs can modulate the interactions with NH 3 and construct pathways in membranes for preferential NH 3 transport, which is expected to overcome the trade-off effect and achieve a desirable separation performance. In this work, four metal ILs (MILs) with different metal centres and hydrogen bond donating ability, including [2-Mim][Li(NTf 2 ) 2 ], [Eim][Li(NTf 2 ) 2 ], [Bmim] 2 [Co(NCS) 4 ], and [Bim] 2 [Co(NCS) 4 ], were incorporated into sulfonated block copolymers to prepare MIL-based hybrid membranes for NH 3 separation. The investigation of structure–performance relationships suggested that the interaction sites and transport channels could be tuned by the MIL type, which greatly affects the NH 3 separation performance of the membranes. The Nexar/2-Mim-Li-10 membrane exhibits NH 3 permeability of 735.6 Barrer with NH 3 /N 2 selectivity of 844.5 and NH 3 /H 2 selectivity of 154.7, which is higher than other MIL-based hybrid membranes owing to self-assembled transport channels and moderate complexation. Increasing the MIL content and feed pressure significantly improved NH 3 separation performance.