【薄膜-亲水疏水性——热浸渍涂晶加旋转晶化制备亲水性ZSM-5沸石膜及其性能表征

尧鹏魁 ^{1, 2}，周志辉^{1, 2}，吴红丹 ^{1, 2}，张青鹏^{1, 2}，徐嘉晨 ^{1, 2}

(1. 武汉科技大学资源与环境工程学院，武汉 430081； 2. 武汉科技大学，冶金矿产资源高效利用与造块湖北省重点实验室，武汉 430081)

摘  要：采用热浸渍涂晶加旋转晶化方法在a-Al₂O₃微孔支撑体上合成了 ZSM-5 沸石膜，并将其应用于异丙醇/水体系渗透汽化脱水。对 ZSM-5 沸石膜的物相组成和显微结构进行表征，研究了合成时间、晶种浓度、制备方法对 ZSM-5 沸石膜性能的影响。结果表明：当第一次涂晶浓度为 2 g/L、二次晶化时间为 28 h 时，制备出的 ZSM-5 沸石膜交互生长良好，膜层致密。 对比3种合成方法(浸渍涂晶加旋转晶化法，热浸渍涂晶加旋转晶化法，热浸渍涂晶加静态晶化法)制备的ZSM-5沸石膜对90 % 异丙醇渗透汽化脱水性能。结果表明：热浸渍涂晶加旋转晶化法更适合制备亲水性 ZSM-5 沸石膜，制备出的沸石膜在 348 K 时对 90%异丙醇进行渗透汽化脱水，渗透通量可达到 1.68 kg/(m²·h)，分离因子为 17 991。

关键词：ZSM-5 沸石膜；旋转晶化；晶体生长；渗透汽化性能

中图分类号：TU502.4   文献标志码：A   

文章编号：0454–5648(2017)01–0070–08

网络出版时间：2016–12–12  09:52:14       

网络出版地址：

http://www.cnki.net/kcms/detail/11.2310.TQ.20161212.0952.003.html

收稿日期：2016–06–12。   

修订日期：2016–07–30。

基金项目：湖北省级教育部门基金项目(Q20121112)。

第一作者：尧鹏魁(1990—)，男，硕士

通信作者：周志辉(1980—)，男，博士，教授。

Introduction

The preparation of ordered zeolite membranes has attracted recent attention due to their regular structures, uniform pore sizes, good thermal stability, mechanical strength and chemical resistance^[1–4]. NaA zeolite membranes are the most widely used membranes due to the high hydrophilicity^[5–9]. However, it was reported that the zeolite membranes have a low thermal stability ^[10–13]. To improve the stability and longevity of zeolite membranes for industrial applications, it is necessary to develop new membranes with a better stability, such as MFI-type zeolite membranes[14], ZSM-5 zeolite membranes[15], Mordenite zeolite membranes[16] and T-type zeolite membranes [17–18]. However, organic templating agents are generally applied in the preparation of these membranes. To remove the organic template and open the zeolite pores, these membranes must be calcined at a high temperature. Zeolite membranes are susceptible to cracking during calcination, and the separation performance of the membranes becomes significantly reduced due to the presence of the cracks ^[19]. To overcome these problems, the preparation of ZSM-5 zeolite membranes without an organic templating agent should be an important issue for the development of zeolite membranes. Recent studies have focused on ZSM-5 zeolite membrane because it has a pore size in the range of many industrially important organic molecules^[20]. Abdollahi et al. synthesized zeolite ZSM-5 layers on the porous alumina substrates, adopting electrophoretic deposition as a seeding method. They found that the separation factors could reach as high as 40 for IPA/water mixtures, and the total membrane flux was approximately 1.75 kg/(m²·h)^[2]. Sun et al. indicated that the separation factor of the Sn-ZSM-5 membrane was 7.7 with a total flux of 0.49 kg/(m²·h) for a 5% (mass fraction) acetic acid aqueous solution at 363 K^[21]. Teli et al. reported that the mixed matrix membranes of H-ZSM-5 membrane containing 5% of zeolite showed a selectivity value of 47 with 0.07 kg/(m²·h) of flux at 20% methanol in a feed mixture at 303 K^[22]. However, those studies above gave a poor selectivity performance. It is vital to develop high-flux and high-selectivity ZSM-5 zeolite membranes for their potential in industrial applications.

In this paper, we synthesized dense template-free hydrophilic ZSM-5 zeolite membranes on the surface of α-Al₂O₃supports using a hot dip-coating seed by a rotated crystallization method. In addition, the effect of synthesis methods on the growth process of ZSM-5 zeolite membrane was also investigated.

Conclusions

The uniform and hydrophilic ZSM-5 zeolite membranes were prepared by the HDRC method on the surface of α-Al₂O₃supports without any templating agent. When the seed concentrations were 2.0 g/L for the first crystallization time and 1.0 g/L for the secondary crystallization time, the flux and separation factor reached 1.106 kg/(m²·h) and 21 942, respectively. The uniform and compact ZSM-5 zeolite membranes with a high separation selectivity were prepared at optimum synthesis time ( i.e., 24 h for the first synthesis time and 28 h for the second synthesis time). Compared to other methods, the surface of the ZSM-5 zeolite membrane prepared by the HDRC method was highly inter-grown, and no exposed areas occurred.

We developed a hot dip-coating with rotated crystallization method for ZSM-5 zeolite membranes with a higher permeate flux and a better selectivity. In further studies, the optimization of synthesis parameters of the developed method will be investigated for the practical application of the ZSM-5 zeolite membranes.

文中部分图表

扩展阅读

含氢硅油表面改性SiO₂疏水增透膜的制备及其表征

孙盈盈，胡星宇，林  海，张慧君，杨文斌，张欣向

(福建农林大学材料工程学院，福州350002)  

摘  要：采用含氢硅油(poly(methylhydrogen)siloxane，PMHS)对溶胶–凝胶法制备的 SiO₂增透膜进行表面修饰，以提高其疏水性能。采用含氢量分别为 0.2%、1.0%和 1.5%的 PMHS，研究改性剂溶液中 PMHS 含量对增透膜性质的影响。结果表明： 经含氢量为 0.2%的 PMHS 改性后的 SiO₂增透膜仍能保持 99.50%以上的透过率；而经含氢量为 1.0%和1.5%的 PMHS 改性的增透膜的透过率下降显著。0.2%PMHS 改性的增透膜的显微结构与未改性的相似，而 1.5%PMHS改性的增透膜孔隙数目明显减少。经含氢量为 0.2%、1.0%和 1.5%的 PMHS 改性的增透膜的疏水性能得到明显地提高。Fourier 红外光谱表明，与未 改性 SiO₂增透膜相比，改性 SiO₂增透膜在 1 257 和 796 cm^–1处出现归属于 Si―CH₃的吸收峰，说明 PMHS 疏水链被成功接枝至 SiO₂增透膜表面。

关键词：溶胶–凝胶法；二氧化硅增透膜；疏水；含氢硅油

中图分类号：TB332    文献标志码：A   

文章编号：0454–5648(2017)01–0150–07

网络出版时间：2016–12–12  09:52:14       

网络出版地址：

http://www.cnki.net/kcms/detail/11.2310.TQ.20161212.0952.015.html

收稿日期：2016–05–16。   

修订日期：2016–07–18。

基金项目：

国家自然科学基金项目(61505029)；

中国石油科技创新基金 项目(2014D-5006-0202)资助。

第一作者：孙盈盈(1993—)，女，硕士研究生。

通信作者：杨文斌(1966—)，男，博士，教授。