离子液体接枝型PI/GO膜的制备及CO2/N2分离的应用

Preparation of ionic liquid grafted-PI/GO membranes and its application in CO2/N2 separation

为了显著提高聚酰亚胺气体分离膜的气体选择性,本文首先通过含有C==N的席夫碱特征结构将胺基化功能性离子液体([NH2ebim][PF6])以侧基的形式接枝于聚酰亚胺主链,形成了离子液体接枝型聚酰亚胺(IL-GPI),然后再通过共混的方法向其中引入氧化石墨烯(GO),制备出IL-GPI/GO混合基质膜,并应用于CO2/N2的分离体系。分别利用傅里叶红外光谱仪(FTIR)、旋转黏度计、扫描电子显微镜(SEM)和动态热机械分析仪(DMA)对IL-GPI/GO混合基质膜进行了表征,并探讨了不同GO含量的IL-GPI/GO混合基质膜对CO2/N2气体分离性能的影响。结果表明,GO在IL-GPI/GO混合基质膜中具有较好的分散性,且混合基质膜的刚性有所增强。对不同GO含量的混合基质膜进行分离性能的比较,发现当GO质量分数为0.8%时,CO2的渗透系数可以提高到16.5Barrer,CO2/N2的选择性可提高到176,突破2008年的Robeson上限。

The study aimed to increase the CO2/N2 selectivity of gas separation membranes.Aminated task specific ionic liquid,1-aminoethyl-3-buthylimidazolium hexafluorophosphate([NH2ebim][PF6]),was grafted to polyimide chains as side groups by the structure of Schiff base of C==N to form ionic liquid grafted polyimide(IL-GPI),and then graphene oxide(GO)was added into IL-GPI by blending and ILGPI/GO mixed matrix membranes were fabricated.IL-GPI/GO mixed matrix membranes were characterized by Fourier transform infrared spectroscopy(FTIR),rotatory viscometer,scanning electronic microscopy(SEM)and dynamic thermomechanical analysis(DMA),respectively.The effect of GO concentrations of IL-GPI/GO mixed matrix membranes on gas permeability was studied.The results showed that GO had good dispersion in MMMs and the rigidity of MMMs was enhanced.After a comparison among these mixed matrix membranes with different GO concentrations,CO2 permeability and CO2/N2 selectivity were improved to 16.5Barrer and 176 when GO mass fraction was 0.8%,respectively,which had exceeded 2008 Robeson’s upper bound.