HF酸刻蚀ZSM-5/PDMS膜渗透汽化透醇性能研究

Pervaporation and performance of HF Acid Etched ZSM-5/PDMS membrane for ethanol Recovery

采用HF酸对3种MFI型沸石(ZSM-5,silicalite-1)进行刻蚀,通过SEM和TEM对刻蚀前后沸石的表面和本体形貌进行了表征,发现酸刻蚀造成沸石表面出现微米级孔洞,但本体仍保留了规则的孔道结构。将刻蚀后的ZSM-5填充至聚二甲基硅氧烷(PDMS)中制备了复合膜,用于乙醇/水混合物的分离,研究了沸石硅铝比、HF酸浓度、操作温度和料液浓度对复合膜渗透汽化分离性能的影响。研究发现HF酸处理,可以有效地提高ZSM-5/PDMS膜的分离因子,由12.3最高上升至16.8([EtOH]=5wt%,50℃),渗透通量稍有下降;随着操作温度的升高,复合膜渗透通量增大,分离因子在50℃达到极大值;料液中乙醇浓度提高,复合膜渗透通量增大,分离因子减小。

Three kinds of MFI-type zeolite（ZSM-5, silicalite-1）were etched with HF acid. The morphology of zeolite before and after HF acid etching was characterized by SEM and TEM. It was found that micro-sized pores appeared on the surface of ZSM-5,while regular pore structures remained in the bulk of ZSM-5. The etched ZSM-5 was filled into PDMS to prepare ZSM-5/PDMS composite membranes, which applied for the pervaporafion separation of ethanol/water mixtures. The effect of various factors,including Si/A1 ratio, HF acid concentration, operation temperature and ethanol feed concen- tration on pervaporation performance were investigated. As the operation temperature increased, the total flux increased, the separation factor reached the maximum value at 50℃. As the ethanol feed concentration increased, the total flux increased, and the separation factor followed the reversed order.