Abstract Mixed-matrix membranes (MMMs) based on metal-organic frameworks (MOFs) molecular sieves have been extensively studied in gas separation due to the high performance and good compatibility of MOF with polymers. In this work, 6FDA-based polyimides MMMs incorporating M-gallate (M = Ni, Co, Mg) MOF particles were fabricated for the first time and investigated for ethylene/ethane (C2H4/C2H6) separation. By reducing synthesis temperature and introducing agitation, the Ni-gallate particles synthesized in flask (Ni-gallate(F)) with optimized conditions are smaller than Ni-gallate synthesized in autoclave (Ni-gallate(A)). The particle size was reduced from ∼7 μm (Ni-gallate(A)) to ∼0.8 μm (Ni-gallate(F)), which enables the formation of uniform MMMs. Because of the better compatibility with polyimide and higher adsorption performance of Ni-gallate than Mg-gallate and Co-gallate, the 6FDA-DAM MMM containing Ni-gallate(F) was capable of simultaneously improving C2H4/C2H6 selectivity and C2H4 permeability whereas the MMM with Mg-gallate(F) or Co-gallate(F) failed in performance enhancement. The 6FDA-DAM MMM with Ni-gallate(F) loading of 20% exhibited optimal C2H4/C2H6 separation performance that surpassed the upper-bound of pure polymers. Detailed analysis of sorption and diffusion coefficients suggested that the enhanced transport properties in Ni-gallate(F) MMMs were attributed to the increase of sorption coefficient provided by the higher C2H4 sorption capacity and selectivity, as well as the favorable gas diffusivity via moderately confined pores of the incorporated Ni-gallate(F) fillers.

中文翻译：

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用于 C2H4/C2H6 分离的 M-gallate MOF/6FDA-聚酰亚胺混合基质膜

摘要 基于金属有机骨架 (MOF) 分子筛的混合基质膜 (MMM) 由于 MOF 的高性能和与聚合物的良好相容性而在气体分离中得到了广泛的研究。在这项工作中，首次制造了包含 M-gallate (M = Ni, Co, Mg) MOF 颗粒的基于 6FDA 的聚酰亚胺 MMM，并研究了乙烯/乙烷 (C2H4/C2H6) 的分离。通过降低合成温度和引入搅拌，在优化条件下在烧瓶中合成的没食子酸镍颗粒(Ni-gallate(F))比在高压釜中合成的Ni-没食子酸酯(Ni-gallate(A))小。粒径从~7 μm（Ni-gallate(A)）减小到~0.8 μm（Ni-gallate(F)），这使得形成均匀的MMMs成为可能。由于与聚酰亚胺更好的相容性和比 Mg-gallate 和 Co-gallate 更高的 Ni-gallate 吸附性能，含有 Ni-gallate(F)的 6FDA-DAM MMM 能够同时提高 C2H4/C2H6 选择性和 C2H4 渗透性，而含有 Mg-gallate(F) 或 Co-gallate(F) 的 MMM 未能提高性能。Ni-gallate(F) 负载量为 20% 的 6FDA-DAM MMM 表现出超过纯聚合物上限的最佳 C2H4/C2H6 分离性能。对吸附和扩散系数的详细分析表明，Ni-gallate(F) MMMs 中增强的输运性能归因于较高的 C2H4 吸附能力和选择性提供的吸附系数的增加，以及通过适度限制的孔隙有利的气体扩散率掺入的 Ni-gallate(F) 填料。