Confined dual functionalized ionic liquids in metal-organic frameworks for selective NH3 adsorption

The capture and separation of ammonia (NH 3 ), a typical hydrogen-rich, carbon-free, but highly corrosive and pungent odorous gas, is significantly important for resource utilization, sustainable development and environment protection. The combination of functionalized ionic liquids (ILs) and porous supports to develop novel porous composites for NH 3 adsorption is an efficient way to achieve the above goals. In this work, dual functionalized IL (DFIL) simultaneously containing Lewis acidic sites and hydrogen bond sites supported porous Zr-MOF (Zr-bptc) with high stability and reversibility are developed for NH 3 adsorption. The DFIL confined in the nanopores not only provides high NH 3 affinity, but also reduces the pore size to form selective NH 3 diffusion pathways. Thus, the highest NH 3 adsorption capacity of 10.26 mmol/g at 1 bar and 25 °C was achieved by DFIL@Zr-bptc-50 wt%. Especially, the optimal composites showed high NH 3 /N 2 IAST of 3146.21 for NH 3 /N 2 (0.5/99.5, v/v) and 593.97 for NH 3 /N 2 (5/95, v/v), which is 269 % and 346 % higher than that of pristine Zr-bptc, respectively, indicating the composites have great potential for low-concentration NH 3 separation. Moreover, the mixed gas breakthrough experiments demonstrated that optimal DFIL@Zr-bptc also exhibits outstanding NH 3 /N 2 separation performance under simulative conditions including ammonia synthesis process and air purification. In addition, the DFIL@Zr-bptc composites show great structural stability and recyclability. This work provides a feasible way to design novel porous IL composites for NH 3 efficient removal and recovery.