American Chemical Society
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Exploring NH3 Transport Properties by Tailoring Ionic Liquids in Pebax-Based Hybrid Membranes

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journal contribution
posted on 2021-06-28, 12:34 authored by Bingbing Yang, Lu Bai, Zhenlei Wang, Haiyan Jiang, Shaojuan Zeng, Xiaochun Zhang, Xiangping Zhang
Ammonia (NH3) separation and recovery from NH3-containing gases favor resource utilization and ecological protection. Ionic liquids (ILs) are promising alternatives to fabricate polymer-based hybrid membranes with excellent and tunable properties. Herein, [Eim]­[NTf2] and [Emim]­[NTf2], with different hydrogen bond donating abilities and viscosities, were used to tailor NH3 transport properties in the membranes for enhancing NH3 separation performance. Poly­(ether-block-amide) (Pebax)/[Eim]­[NTf2] membranes exhibit superior NH3 permeability of 2118.7 Barrer with NH3/N2 and NH3/H2 selectivities of 467.0 and 127.2, respectively. NH3 solubility in Pebax/[Eim]­[NTf2] membranes increases significantly when increasing the IL content, while the solubility in Pebax/[Emim]­[NTf2] membranes is almost unchanged, mainly because the hydrogen bond interaction between NH3 and [Eim]­[NTf2] is stronger. NH3 diffusion in Pebax/[Eim]­[NTf2] membranes decreases when increasing the IL content, while the diffusion in Pebax/[Emim]­[NTf2] membranes exhibits the reverse trend, corresponding to NH3 diffusion properties in pure ILs. Therefore, NH3 solubility is the more dominant factor in improving NH3 permeability in the membranes.