Polyelectrolytes have been reported to display gas permeation properties that can be of significant interest for CO₂ capture applications, especially when they are fully hydrated. In this work, hybrid membranes prepared by co-casting an ionic liquid (IL), 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF₄]), with Nafion have been investigated for use in carbon capture. Gas permeabilities of different gaseous species have been measured for IL concentrations up to 40 wt%. Moreover, the effect of water vapor on gas permeation is examined with humidified CO₂/N₂ gas mixtures at various relative humidity (RH) levels. These experiments reveal that CO₂ permeability is greatly enhanced upon addition of the IL and in the presence of water in the gas stream, most likely due to the formation of IL nanochannels in the Nafion matrix. Small-angle X-ray scattering confirms changes in the nanostructure at different IL loading levels. Hybrid membranes containing 40 wt% [Bmim][BF₄] exhibit a mixed-gas CO₂ permeability of 390 Barrer with a corresponding CO₂/N₂ selectivity of ∼30 at 100% RH, which is more than 3× that of the permeability measured from the same IL-containing membrane in the dry state and more than 200× higher than that of dry Nafion. Such improvements suggest the existence of a synergetic relationship between the IL and water vapor with regard to Nafion gas-transport properties, yielding superior separation performance with an enhanced gas flux compared to extruded Nafion membranes. These results represent a viable fabrication strategy for the production of thin Nafion-based membranes for CO₂ capture.

中文翻译：

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Nafion / IL杂化膜具有可调节的纳米结构，可增强CO ₂分离：离子液体和水蒸气的影响

据报道，聚电解质表现出气体渗透性能，这对于CO ₂捕集应用可能具有重大意义，特别是当它们完全水合时。在这项工作中，已研究了通过与Nafion共浇铸离子液体（IL）1-丁基-3-甲基咪唑鎓四氟硼酸酯（[Bmim] [BF ₄ ]）制备的杂化膜，用于碳捕集。对于高达40 wt％的IL浓度，已经测量了不同气体种类的气体渗透率。此外，用各种相对湿度（RH）水平的加湿CO ₂ / N ₂气体混合物检查了水蒸气对气体渗透的影响。这些实验表明，CO ₂添加IL并在气流中有水的情况下，通透性会大大提高，这很可能是由于在Nafion基质中形成了IL纳米通道。小角度X射线散射证实了在不同的IL负载水平下纳米结构的变化。包含40 wt％[Bmim] [BF ₄ ]的杂化膜显示390 Barrer的混合气体CO ₂渗透率以及相应的CO ₂ / N ₂在100％RH下的选择性约为30，这比相同的含IL膜在干燥状态下测得的渗透率高3倍，比干燥的Nafion高200倍以上。此类改进表明，就Nafion气体传输特性而言，IL和水蒸气之间存在协同关系，与挤出的Nafion膜相比，可产生出众的分离性能，并具有增强的气体通量。这些结果代表了生产用于CO ₂捕集的基于Nafion的薄膜的可行制造策略。