Preparation of Zeolite NaA Membranes on Macroporous Alumina Supports by Secondary Growth of Gel Layers

详细信息    查看全文

• 作者：Jie Ma ; Jia Shao ; Zhengbao Wang ; Yushan Yan
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2014
• 出版时间：April 9, 2014
• 年：2014
• 卷：53
• 期：14
• 页码：6121-6130
• 全文大小：1037K
• 年卷期：v.53,no.14(April 9, 2014)
• ISSN：1520-5045

文摘

Zeolite NaA membranes are synthesized on tubular 伪-Al₂O₃ supports by the secondary growth of gel layers. The gel layer is prepared by wetting鈥搑ubbing hydrogel with a composition similar to the secondary synthesis solution xNa₂O:2SiO₂:Al₂O₃:150H₂O. The hydrogel鈥檚 good uniformity makes it easier to gain a uniform gel layer. Zeolite NaA membranes are characterized by SEM and pervaporation separation of a 90 wt % ethanol/water mixture at 75 掳C. The effects of the pretreatment time, pretreatment temperature, gel loading, and Na₂O/Al₂O₃ ratio of the hydrogel on properties of zeolite NaA membranes are investigated. It is found that zeolite NaA membranes with high separation factors up to 10鈥?00 can be obtained by secondary growth of gel layers. The optimal pretreatment conditions of the hydrogel are as follows: pretreatment temperature, 50 掳C; pretreatment time, 鈮?8 h; and gel loading, 0.6鈥?.9 mg/cm². The optimal composition of the hydrogel is 2.2Na₂O:2SiO₂:Al₂O₃:150H₂O, which is the same as the synthesis solution. Like crystal seeds, the gel layer improves the zeolite membrane formation on the support surface, and the role of the gel layer becomes more significant with greater amounts of crystals.