用于分离DMF/H_2O体系的Me-silicalite-1渗透汽化分子筛膜的制备

Preparation of Me-silicalite-1 Zeolite Membrane for Pervaporation Separation of DMF/H_2O Mixtures

采用二次生长法制备了用于渗透汽化分离DMF/H2O体系的杂原子取代Me-silicalite-1/α-Al2O3(Me=Co、Fe)分子筛复合膜,通过X射线衍射(XRD)、扫描电镜(SEM)、傅里叶红外光谱(FT-IR)和紫外漫反射(UV-Vis)等方法对分子筛膜进行表征,结果表明金属离子进入分子筛骨架。渗透汽化实验显示,金属离子掺杂的silicalite-1/α-Al2O3分子筛复合膜,具有较好的分离性能且优先透过有机胺,有利于工业中DMF溶剂的回收和利用。随着操作温度升高,分离因子减小,渗透通量增加。40℃分离质量分数为5%的DMF/H2O混合液时,Co-silicalite-1/α-Al2O3分子筛膜和Fe-silicalite-1/α-Al2O3分子筛膜的分离因子分别为4.4和2.9,渗透通量分别为0.66和0.84 kg·m-2·h-1。

Me-silicalite-1（Me=Fe, Co） zeolite composite membranes supported on α-alumina discs were prepared by a seeded secondary growth method and used in pervaporation separation of dimethylformamide （DMF）/water mixtures. The zeolite membranes were characterized by XRD, SEM, FT-IR and UV-Vis technologies. The results indicated that metal ions were substituted into zeolite framework. The pervaporation experiments showed that metal doping could improve the separation performance of silicalite-1/α-Al2O3 zeolite composite membranes and change the membrane surface to organic permselectivity, which is conducive to the recovery of DMF solvent from dilute DMF wastewater in industry. As operation temperature increased, the permeate flux of membranes was enhanced but the separation factor decreased. The separation factor of Co-silicalite-1/α-Al2O3 and Fe-silicalite-1/α-Al2O3 zeolite membranes for 5%（wt） DMF/H2O mixture at 40℃were 4.4 and 2.9, and the permeate flux of them were 0.66 and 0.84 kg？m-2？h-1, respectively.