聚甲基丙烯酸二甲氨基乙酯气体分离膜的制备与分离性能

Preparation and separation performance of interfacially crosslinked gas separation membrane of PDM

为提高气体分离膜的渗透性能,将界面交联法应用于制备气体分离用超薄复合膜,采用侧链具有反应性的聚合物聚甲基丙烯酸二甲氨基乙酯(PDM)为涂层材料,通过PDM涂层与交联剂溶液之间的固-液界面反应制膜,并采用扫描电镜(SEM)和X射线光子能谱仪(XPS)对膜的形貌及表面化学结构进行表征。结果表明:界面反应形成的PDM交联层具有不对称结构,表面可以充分交联并提供分离性能,表面以下疏松的交联结构有利于气体渗透;当分离因子相同时,界面交联膜的渗透通量更高,在跨膜压差为300kPa、操作温度为23℃时,界面交联膜的CO2渗透速率为85GPU,本体交联膜的CO2渗透速率为30GPU,CO2/N2理想分离因子为50。

In order to enhance the permeability of gas separation membrane,this work presented a method for preparing thin-film composite membranes for gas separation via an interfacial crosslinking.A side-chain active polymer,poly(N,N-dimethylaminoethyl methacrylate)(PDM) was employed as the coating material.A solid-liquid interfacial reaction,occurring between the preformed solid PDM layer and acrosslinker solution,was exploited for the film formation.The morphology and the surface chemical structure of the membrane were characterized by SEM and XPS.The results showed that the interfacially formed PDM layer has a non-uniform crosslinking structure.The surface layer can be sufficiently crosslinked,which is responsible for the selectivity.The less crosslinked loose structure beneath the surface layer favors gas permeation.When the separation factor is the same,the permeation flux of the interfacially crosslinked membrane is higher than that of the bulk crosslinked membrane.When the transmembrane pressure difference is 300 kPa and the operating temperature is 23 ℃,the interfacially crosslinked membrane has a CO2 permeance of 85 GPU,while the bulk crosslinked membrane has a CO2 permeance of 30 GPU,and the ideal separation factor of CO2/N2 is 50.