混合基质膜结合了无机膜和聚合膜的优点,有望突破气体分离膜中选择性和渗透性之间存在的“Trade-off”限制。然而,提高气体分离性能的关键是选择结构与性能相匹配的无机填料和高分子材料,以及优化混合基质膜的制备工艺。选择多孔米糠基活性炭(RBC)作为填料,高CO2亲和能力的聚醚嵌段酰胺(Pebax)为聚合物基质,利用溶液浇铸技术制备混合基质膜(Pebax/RBC)。采用BET比表面积和红外光谱(FT-IR)表征了RBC的微观结构,并借助FT-IR、X射线衍射(XRD)和热重(TG/DTG)对膜结构和热稳定性进行了表征。研究了RBC添加量、气体压力、测试温度和湿膜厚度对CO2分离性能的影响,并采用混合气作为进料气探究了混合基质膜的气体分离性能及稳定性。结果表明:RBC被高分子链紧密缠结形成完好的有机-无机相界面,并且增加了高分子的链间距。制备的混合基质膜的渗透性可达580Barrer和CO2/N2选择性为61,超过了2008年的Robeson上限。此外,进料气为混合气(CO2/N2=15/85,体积分数)的测试条件下,Pebax/RBC连续测试360h后,其平均CO2渗透性和CO2/N2选择性仍能保持463Barrer和49。
Mixed matrix membranes,which combine the advantage of inorganic membrane and polymer membrane,are expected to break the “Trade-off” effect between selectivity and permeability in gas separation membranes.However,the key to improve gas separation performance is the selection of inorganic fillers and polymer materials with compatible structure and performance,as well as the optimization of the preparation of mixed matrix membranes.In this paper,porous rice bran-based activated carbon (RBC) was selected as the filler and polyether block amide (Pebax) with high CO2 affinity as the polymer matrix,and the mixed matrix membranes (Pebax/RBC) were prepared by solution casting technology.The microstructure of RBC was characterized by BET and FT-IR,and the structure and thermal stability of the membranes were characterized by FT-IR,XRD and TG/DTG.The effects of RBC addition amount,gas pressure,test temperature and wet membrane thickness on the performance of CO2 separation performance were studied,and the gas separation performance and stability of the mixed matrix membranes were investigated by using the mixed gas as the feed gas.The results showed that the RBC were tightly entangled with the polymer chains to form a good organic-inorganic phase interface,and the chain spacing of the polymer was increased.The prepared mixed matrix membranes had a CO2 permeability of up to 580 Barrer and a CO2/N2 selectivity of 61,exceeding the 2008 Robeson upper bound.In addition,under the test condition of mixed feed gas (CO2/N2=15/85 vol.%),the average CO2 permeability and CO2/N2 selectivity of Pebax/RBC remained at 463 Barrer and 49 after 360 h of continuous testing.
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