Pebax-based composite membranes with high gas transport properties enhanced by ionic liquids for CO2 separation
Pebax-based composite membranes with high gas transport properties enhanced by ionic liquids for CO2 separation
复制标题
用于 CO2 分离的离子液体增强了具有高气体传输性能的 Pebax 复合膜
DOI：
10.1039/c6ra27221e
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发表时间：
2017-01-01
期刊：
影响因子：
3.9
通讯作者：
Zhang, Suojiang
中科院分区：
文献类型：
--
作者：
Li, Mengdie;Zhang, Xiangping;Zhang, Suojiang
膜分离技术是一种高效、经济地分离二氧化碳的可行方法。为了提供气体分离性能的协同增强，有机聚合物（Pebax 1657），沸石咪唑酸框架-8 （ZIF-8）纳米颗粒和离子液体（IL）被整合在一起开发了三组分复合膜。为了使三组分膜具有较高的分离性能，首先研究了IL阴离子和ZIF-8含量对其透气性和选择性的影响。它们是基于双（三氟甲基磺酰基）亚胺（[NTf2]）、二氰酰胺（[DCA]）和四氟硼酸盐（[BF4]）不同阴离子的1-丁基-3-甲基咪唑（[Bmim]）阳离子。在23℃和1 bar条件下，研究了所制备膜的气体输运特性。结果表明，IL的阴离子是决定膜对CO2渗透性的关键因素，这与纯IL中CO2溶解度的原理相似。此外，ZIF-8可以提高Pebax/ZIF-8膜的CO2扩散系数和溶解度系数，从而使CO2渗透率提高两倍。对于Pebax/ZIF-8(15%)/[Bmim][NTf2]膜，[Bmim][NTf2]作为低分子量添加剂，使膜具有更大的非晶态结构和更高的FFV（分数自由体积），有利于气体扩散。IL的加入可以改善无机颗粒与聚合物基体的相容性；因此，非选择性空隙减少，从而导致更高的CO2/N2选择性。在不牺牲CO2/N2选择性的情况下，Pebax/ZIF-8(15%)/IL（80%）膜的CO2渗透率是纯Pebax膜的4.3倍。因此，Pebax/ZIF-8/IL膜的高气体输运特性使其成为二氧化碳有效分离材料的有希望的候选材料。
Membrane-based separation technology has been reported as one of the possible methods to efficiently and economically separate carbon dioxide (CO2). To provide synergistic enhancements in the gas separation performance, organic polymer (Pebax 1657), zeolite imidazolate framework-8 (ZIF-8) nanoparticles, and ionic liquid (IL) have been integrated to develop three-component composite membranes. To achieve high separation performance of three-component membranes, the effects of IL anions and ZIF-8 content on gas permeability and selectivity were investigated first. The ILs were 1-butyl-3-methyl imidazolium ([Bmim]) cation based on different anions of bis(trifluoromethylsulfonyl)imide ([NTf2]), dicyanamide ([DCA]), and tetrafluoroborate ([BF4]). Gas transport properties of all the prepared membranes were investigated at 23 °C and 1 bar. The results showed that the anion of IL is a key factor to determine the CO2 permeability of the membranes, which is similar to the principle of CO2 solubility in pure ILs. In addition, ZIF-8 could increase both CO2 diffusivity and solubility coefficients of the Pebax/ZIF-8 membranes, resulting in a two-fold increase in the CO2 permeability. For the Pebax/ZIF-8(15%)/[Bmim][NTf2] membranes, it has been revealed that [Bmim][NTf2] acts as a low molecular weight additive, leading to a more amorphous structure and a higher FFV (fractional free volume) of the membranes, which are beneficial for gas diffusion. The addition of IL can improve the compatibility between the inorganic particles and the polymer matrix; thus, the non-selective voids decrease, which leads to a higher CO2/N2 selectivity. The CO2 permeability of the Pebax/ZIF-8(15%)/IL(80%) membrane was 4.3 times that of the pure Pebax membrane without sacrificing the CO2/N2 selectivity. Therefore, the high gas transport properties of the Pebax/ZIF-8/IL membranes make them promising candidates for CO2-effective separation materials.