Mixed matrix membranes containing Cu-based metal organic framework and functionalized ionic liquid for efficient NH3 separation

Abstract

Membranes that both have high gas permeability and selectivity is still challenging. Aiming to efficiently separate and purify ammonia-containing gases, this work constructed a novel ternary mixed matrix membranes (MMMs) by introducing functionalized ionic liquid ([Bim][NTf2]) and Cu-based metal organic framework (CuBTC). It was proved that the interaction networks consisted of hydrogen bonding and electrostatic interactions are formed in the IL-based MMMs, leading to the improved compatibility, decreased crystallinity and amorphous morphology. The ammonia separation performance was evaluated through pure gases and mixed gases. The PCu3-IL100 MMM exhibits great ideal selectivities (αNH3/N2 = 530.1 and αNH3/H2 = 94.2) and optimal NH3 permeability up to 3680.0 barrer, which is 260% and 129% higher than the pristine Pebax membrane and the PCu3 MMM, respectively. The improving NH3 separation performance is attributed to the synergistic interaction of hydrogen bonding and Lewis acid-base between IL-based MMMs and NH3 molecules, significantly increasing NH3 solubility coefficient and solubility selectivity. The IL-based MMMs also show exceptional NH3 mixed separation performance and long-term operation stability.