Porous multi-site ionic liquid composites for superior selective and reversible adsorption of ammonia
Shuang Zheng, Qiuxia Xu, Shaojuan Zeng, Guilin Li, Haiyan Jiang, Xueqi Sun, Xiangping Zhang
Abstract
Ionic liquids (ILs) with low vapor pressure, tunable structures and good NH 3 affinity provide an inspiring way to efficiently capture NH 3 . However, the high viscosity of most ILs limited mass transfer, which incumbers their industrial applications. Besides, how to simultaneously achieve high selectivity, capacity and reversibility of NH 3 still face great challenge. Herein, four novel hydroxyl ammonium protic ILs (HAPILs), including methyldiethanolammonium trifluoromethanesulfonate ([MDEAH][CF 3 SO 3 ]), triethanolammonium trifluoromethanesulfonate ([TEAH][CF 3 SO 3 ]), dimethylethanolammonium trifluoromethanesulfonate ([DMEAH][CF 3 SO 3 ]) and diethylethanolammonium trifluoromethanesulfonate ([DEEAH][CF 3 SO 3 ]), with multiple hydrogen bonding donors that can interact with more over two NH 3 molecules were designed and synthesized, and were further supported onto porous molecular sieves to overcome the above problem. Among the prepared porous HAPIL composites, 50 wt% [TEAH][CF 3 SO 3 ]@MCM-41 showed the highest NH 3 /CO 2 selectivity of 62 under 313 K and 0.1 MPa compared with the state-of-the-art values, along with high capacity of 114.3 mgNH 3 /g-adsorbent. The excellent NH 3 adsorption performance was attributed to the synergistic interaction of mesoporous effect and multiple hydrogen bonding between NH 3 and HAPILs. Furthermore, the porous HAPIL composites exhibited great recyclability after six cycles, revealing great potentials in industrial application of efficient and reversible NH 3 separation.