以二维材料构筑纳米片膜研究进展
Progress in Fabrication of Nanosheet Membranes with Two-Dimensional Materials
DOI: 10.12677/MS.2018.86087, PDF, HTML, XML,    科研立项经费支持
作者: 郑璐康, 周智慧, 吴云琴, 陈 琦, 汤会玲, 张豪益, 肖 强:浙江师范大学含氟新材料研究所,浙江 金华
关键词: 二维纳米片分离性能MFI纳米片Two-Dimensional Nanosheets Separation Property MFI Nanosheet
摘要: 二维材料作为一类新兴材料,具有较高的面厚比和比表面积,在构筑膜材料方面具有天然优势。近些年一些二维材料如石墨烯纳米片、MOF和COF纳米被广泛用于基本结构单元制备纳米片膜。本文介绍了制备纳米片膜的二维纳米片材料,重点介绍了二维沸石纳米片材料。由于沸石分子筛膜具有微孔性、耐高温、耐溶胀、分子筛分等特性,在分离膜领域具有广泛的应用前景。
Abstract: Two-dimensional materials, as a new type of materials, exhibit superior advantages in the fabrica-tion of membrane materials due to their high aspect ratio and specific surface areas. In recent years, some two-dimensional materials such as graphene nanosheets, MOF and COF nanosheets have been widely used in the preparation of nanosheets membrane as basic structural units. In this paper, two-dimensional nanosheet materials for preparing nanosheet membranes are introduced, with emphasis on two-dimensional zeolite nanosheet materials. Zeolite molecular sieve has wide application prospect in separation membrane field because of its microporous, high temperature resistant, swelling resistant and molecular sieve grading characteristics.
文章引用:郑璐康, 周智慧, 吴云琴, 陈琦, 汤会玲, 张豪益, 肖强. 以二维材料构筑纳米片膜研究进展[J]. 材料科学, 2018, 8(6): 736-741. https://doi.org/10.12677/MS.2018.86087

1. 引言

随着能源危机的加剧和工业生产规模的扩大,发展低能耗的分离过程有着积极的社会意义和经济效益,用更高效的方式替代或耦合精馏等热驱动过程是重要的节能减排措施。膜分离技术具有过程简单、设备体积小、无相变、操作简便、无二次污染等优势,广泛地应用于海水脱盐、气体分离、化学合成和纯化等领域。膜是膜分离技术的核心,膜材料的性质和化学结构对膜分离性能起着决定性的影响。超薄的二维纳米材料 [1] 具有片状结构,平面尺寸可达几个微米甚至更大,但是只有单个或几个原子厚度。由于二维材料具有较高的面厚比,因此在构筑膜材料方面具有天然优势 [2] [3] [4] [5] [6] ,在膜分离领域已经得到广泛应用。

2. 二维材料

二维材料具有独特物理化学性质,目前处于飞速发展阶段。如石墨烯、二维过渡金属碳化物或碳氮化物 [7] 、贵金属 [8] [9] [10] [11] 、金属有机框架材料(MOF) [12] [13] [14] 、共价有机框架材料(COF) [15] 、聚合物 [16] [17] [18] [19] 、黑磷 [20] [21] 等,以其二维材料作为膜材料的构筑单元制备的二维纳米片膜展现了较好的分离性能。其中以石墨烯、MOF、COF纳米片作为构筑单元制备二维纳米片膜这一工作备受瞩目。

3. 二维材料纳米片膜

3.1. 石墨烯纳米片膜

石墨烯的发现极大的推动了二维材料在膜分离等领域的研究。石墨烯纳米片厚度接近单原子层、柔韧性高、化学性质稳定等一些特性,因此石墨烯纳米片可以作为构筑石墨烯膜材料的基本单元,石墨烯超薄膜对包括He在内的小分子具有良好的分离性能,以石墨烯及其衍生物如氧化石墨烯(GO) [22] 等原料制备的气体分离膜具有优异的分离性能。Shen等人 [23] 以GO纳米片为填充材料制备了GO/聚醚嵌段酰胺(PEBA)混合基质膜,测试结果表明所制备的混合基质膜对CO2的渗透系数为110 barrer,CO2/N2的选择性为80。Ha等人 [24] 制备了GO/聚二甲基硅氧烷(PDMS)混合基质膜,8 wt%的混合基质膜相对于纯PDMS膜来说CO2/N2和CO2/CH4的选择性提高了两倍,但是H2、O2、N2、CH4和CO2气体的渗透系数却降低了一倍。这是因为石墨烯是无孔材料,分子传输是依靠石墨烯纳米片层间的纳米片通道来达到的,GO纳米片的加入增加了气体的扩散路径,降低了气体的渗透速率。Li等人 [25] 通过超声方法剥离得到GO纳米片,制备了厚度为9 nm的纳米片膜,借助于纳米片层之间的缝隙,得到的GO膜显示了较高的H2分离性能,因其为无孔材料并没有达到较高的气体渗透量。

3.2. MOF和COF纳米片膜

由于石墨烯片为无孔材料,石墨烯片膜在层间迁移的分离机制限制了膜分离效率的提高。相比之下,多孔性的二维纳米片骨架是制备膜材料更为理想的构筑单元 [26] 。MOF纳米片是一种新型的具有纳米级孔道的多孔材料。杨维慎课题组 [27] 合成了一种名为Zn2(bim)4的层状MOF前驱体,其层间主要以较弱的范德华力连接,采用低速湿球磨结合超声的方法将其剥离,制备了大小为600 nm、厚度为1 nm、孔径为0.21 nm的MOF纳米片,以其为结构单元制备了超薄MOF膜,借助于MOF骨架中微孔的分子筛分作用,得到的MOF膜显示了较高的气体渗透速率和分子尺寸选择性。接着该课题组合成出了一种全新的MOF前驱体Zn2(bim)3并用温和的物理方法进行剥离制备了双层厚度的MOF纳米片,通过前期开发的热组装方法制备了厚度为10 nm的超薄MOF纳米片膜,该膜对H2/CO2混合气体具有较高的分离性能,不同于其它二维纳米片膜,该膜随着测试温度的升高,在CO2渗透量维持不变的情况下,其对H2的渗透量可升高至8 × 10−7 mol∙m−2∙s−1∙Pa−1,分离系数高达166 [28] 。王焕庭课题组 [29] 直接将合成的二维层状沸石类咪唑骨架(ZIF)——ZIF-L铺到多孔载体上,经二次生长后制备了晶体取向ZIF膜,显示了一定的H2/N2和H2/CO2分离性能。Jiang等人 [30] 利用Cu(II)和tri(beta-diketone)合成出了新型二维MOF结构,将该纳米片以抽滤沉积的方法制备了复合MOF纳米片膜,该膜可阻隔尺寸高于2.4 nm的金纳米颗粒。

COF作为一种与MOF材料类似的新型材料,同样具有独特的有序多孔结构,是潜在的分离膜材料。仲崇立课题组 [31] 通过氧化石墨烯(GO)辅助的层层叠装方法将二维共价三嗪基骨架(CTF-1)纳米片沉积制备了超薄共价有机骨架COF (Covalent Organic Framework)膜,该膜在H2/CO2气体分离中显示了较高的H2渗透速率。由此看出,由多孔性的MOF及COF纳米片作为构筑单元制备的二维片膜展现了较好的分离性能。

3.3. 二维沸石纳米片膜

相比于石墨烯类纳米片膜、MOF及COF纳米片膜,沸石分子筛膜具有微孔性、耐高温、耐溶胀、分子筛分等特性,在高效膜分离过程中(如:CO2/H2气体分离、醇/水分离、二甲苯筛分等)具有广阔的应用前景 [32] [33] [34] 。以二维沸石纳米片为构筑单元制备膜材料格外具有吸引力,而如何获得大尺寸、单层、开孔的沸石纳米片是成功制备沸石分离膜的关键。

MFI沸石具有规则的二维交叉孔道结构,沿a轴的正弦孔道为5.4 Å × 5.1 Å,沿着b轴的直孔道为5.4 Å × 5.6 Å。MFI沸石膜在有机蒸汽脱除、醇–水渗透气化等过程中显示了较高的分离效率。2009年Ryoo课题组 [35] 通采用一种具有长链烷基和双季铵盐组成的有机结构导向剂(OSDA)首次合成了具有多层结构的MFI (ML-MFI)沸石,其结构是由1.5晶胞厚度的MFI纳米片沿b轴方向组装构成。2011年Tsapatsis课题组 [36] 通过聚苯乙烯(PS)熔融共混方式剥离ML-MFI沸石,得到了可分散的二维MFI沸石纳米片,将其沉积到多孔氧化铝载体上,经二次生长制备了超薄、b轴取向的MFI沸石分子筛膜。最近他们又用bis-1,5(tripropyl ammonium)pentamethylene diiodide (dC5)为模板剂,直接合成了2.5晶胞厚度的MFI沸石纳米片,通过抽滤方法沉积到多孔氧化铝载体上,经二次生长制备了具有超高通量和选择性的MFI型沸石膜 [37] 。然而,无论是熔融共混法剥离ML-MFI沸石纳米片还是dC5沸石纳米片中均含有模板剂,孔未打开,直接组装成纳米片膜经焙烧除模板剂开孔后,并无气体分离性能,需经二次生长消除膜内晶间空隙,再高温焙烧除去有机模板剂后才能获得具有分离性能的MFI沸石膜 [36] 。然而高温焙烧通常会引起沸石膜层出现晶间孔、缺陷甚至破裂,大大降低沸石膜的分离性能 [38] 。

最近我们将ML-MFI沸石用熔融共混方法剥离后,采用piranha溶液(3H2SO4-H2O2)移除模板剂,得到了开孔的MFI沸石纳米片,通过简单抽滤的方式,沉积在多孔高分子载体聚苯并咪唑(PBI)上,未经二次生长直接制备了MFI沸石纳米片膜,该膜显示了一定的丁烷异构体选择性。该结果表明,采用开孔的MFI沸石纳米片作为构筑单元,能够在高分子载体上不经二次生长直接制备沸石膜 [39] 。最近我们又首先采用piranha溶液除去ML-MFI中的有机模板剂,削弱层间作用力,然后在经超声得到开孔剥离的MFI沸石纳米片,并以此为构筑单元采用抽滤的方法在多孔氧化铝载体上不经二次生长制备了MFI沸石纳米片膜,该膜对丁烷异构体的选择性为4.1~5.8,正丁烷通量为2.2 × 10−7~4.1 × 10−7 mol∙m−2∙s−1∙Pa−1。以二维MFI沸石纳米片为构筑单元,不经二次生长直接制备MFI沸石纳米片膜,可克服二次生长带来的弊端,丰富载体的选择,具有很好的科学意义和应用前景。

4. 展望

通过层层组装方法制备了有丁烷异构体选择性的沸石纳米片膜,但其分离性能仍大幅低于Agrawal等人 [40] 通过二次并焙烧后制备的MFI沸石膜的丁烷异构体的选择性(n/i~47-62)。通过采用进一步纯化的MFI沸石纳米片和更优化的纳米片排列方式,期望得到具有更高选择性的MFI沸石纳米片膜。

基金项目

浙江省大学生科技创新活动计划暨新苗人才计划项目(2017R404017)。

NOTES

*通讯作者。

参考文献

[1] Tan, C., Cao, X., Wu, X.J., et al. (2017) Recent Advances in Ultrathin Two-Dimensional Nanomaterials. Chemical Re-views, 117, 6225-6331.
https://doi.org/10.1021/acs.chemrev.6b00558
[2] Cussler, E.L. (1990) Membranes Containing Selective Flakes. Journal of Membrane Science, 52, 275-288.
https://doi.org/10.1016/S0376-7388(00)85132-7
[3] Liu, G., Jin, W. and Xu, N. (2016) Two-Dimensional-Material Membranes: A New Family of High-Performance Separation Membranes. Angewandte Chemie International Edition, 55, 13384-13397.
https://doi.org/10.1002/anie.201600438
[4] Kang, K., Lee, K.H., Han, Y., et al. (2017) Layer-by-Layer As-sembly of Two-Dimensional Materials into Wafer-Scale Heterostructures. Nature, 358, 907-911.
https://doi.org/10.1038/nature23905
[5] Zhu, X., Tian, C., Dothanh, C.L., et al. (2017) Two-Dimensional Ma-terials as Prospective Scaffolds for Mixed-Matrix Membrane-Based CO2 Separation. Chemsuschem, 10, 3304-3316.
https://doi.org/10.1002/cssc.201700801
[6] Li, D., Wei, Y., Li, L., et al. (2018) Mxene Molecular Sieving Membranes for Highly Efficient Gas Separation. Nature Communications, 9, 155-162.
https://doi.org/10.1038/s41467-017-02529-6
[7] Naguib, M., Mochalin, V.N., Barsoum, M.W., et al. (2014) 25th Anniversary Article: Mxenes: A New Family of Two-Dimensional Materials. Advance Materials, 26, 992-1005.
https://doi.org/10.1002/adma.201304138
[8] Fan, Z.X., Huang, X., Tan, C.L., et al. (2015) Thin Metal Nanostructures: Synthesis, Properties and Applications. Chemical Science, 46, 95-111.
https://doi.org/10.1039/C4SC02571G
[9] Niu, J., Wang, D., Qin, H., et al. (2014) Novel Polymer-Free Iridescent Lamellar Hydrogel for Two-Dimensional Confined Growth of Ultrathin Gold Membranes. Nature Communication, 5, 3313-3320.
https://doi.org/10.1038/ncomms4313
[10] Huang, X.Q., Tang, S.H., Mu, X.L., et al. (2011) Freestanding Palla-dium Nanosheets with Plasmonic and Catalytic Properties. Nature Nanotechnology, 6, 28-32.
https://doi.org/10.1038/nnano.2010.235
[11] Duan, H.H., Yan, N., Yu, R., et al. (2014) Ultrathin Rhodium Nanosheets. Nature Communication, 5, 3093-3111.
https://doi.org/10.1038/ncomms4093
[12] Ding, Y., Chen, Y.P., Zhang, X., et al. (2017) Controlled Intercalation and Chemical Exfoliation of Layered Metal-Organic Frameworks Using a Chemically Labile Intercalating Agent. Journal of the American Chemical Society, 139, 23852-23858.
https://doi.org/10.1021/jacs.7b04829
[13] Zhao, M., Lu, Q., Ma, Q., et al. (2017) Two-Dimensional Metal-Organic Framework Nanosheets. Small Methods, 1. 1-2.
https://doi.org/10.1002/smtd.201600030
[14] Lu, Q.P., Zhao, M.T., Chen, J.Z., et al. (2016) In-Situ Synthesis of Metal Sulfide Nanoparticles Based on Two-Dimensional Metal-Organic Framework Nanosheets. Small, 12, 4669-4674.
https://doi.org/10.1002/smll.201600976
[15] Colson, J.W., Woll, A.R., Mukherjee, A., et al. (2011) Oriented 2D Covalent Organic Framework Thin Films On Single-Layer Graphene. Science, 332, 228-231.
https://doi.org/10.1126/science.1202747
[16] Kissel, P., Murray, D.J., Wulftange, W.J., et al. (2014) A Nanopo-rous Two-Dimensional Polymer by Single-Crystal-to-Single-Crystal Photopolymerization. Nature Chemistry, 6, 774-778.
https://doi.org/10.1038/nchem.2008
[17] Kory, M.J., Wörle, M., Weber, T., et al. (2014) Gram-Scale Synthesis of Two-Dimensional Polymer Crystals and Their Structure Analysis by X-Ray Diffraction. Nature Chemistry, 6, 779-784.
[18] Tan, C.L., Qi, X.Y., Huang, X., et al. (2014) Single-Layer Transition Metal Dichalcogenide Nanosheet-Assisted Assembly of Aggregation-Induced Emission Molecules to Form Organic Nanosheets with Enhanced Fluorescence. Advanced Materials, 26, 1735-1739.
https://doi.org/10.1002/adma.201304562
[19] Cai, S.L., Zhang, W.G., Zuckermann, et al. (2015) The Organic Flatland-Recent Advances in Synthetic 2D Organic Layers. Advanced Materials, 27, 5762-5770.
https://doi.org/10.1002/adma.201500124
[20] Liu, H., Du, Y., Deng, Y., et al. (2015) Semiconducting Black Phosphorus: Synthesis, Transport Properties and Electronic Applications. Chemical Society Reviews, 44, 2732-2743.
https://doi.org/10.1039/C4CS00257A
[21] Eswaraiah, V., Zeng, Q., Long, Y., et al. (2016) Black Phosphorus: Next Generation Nanomaterial for Electronic, Optoelectronic and Other Applications. Small, 12, 3480-3502.
https://doi.org/10.1002/smll.201600032
[22] Yoo, B.M., Shin, H.J., Yoon, H.W., et al. (2014) Graphene and Graphene Oxide and Their Uses in Barrier Polymers. Journal of Applied Polymer Science, 131, 1-15.
https://doi.org/10.1002/app.39628
[23] Shen, J., Liu, G., Huang, K., et al. (2015) Membranes with Fast and Selective Gas-Transport Channels of Laminar Graphene Oxide for Efficient CO2 Capture. Angewandte Chemie In-ternational Edition, 54, 578-582.
[24] Ha, H., Park, J., Ando, S., et al. (2016) Gas Permeation and Selectivity of Poly(dimethylsiloxane)/Graphene Oxide Composite Elastomer Membranes. Journal of Membrane Science, 518, 131-140.
https://doi.org/10.1016/j.memsci.2016.06.028
[25] Li, H., Song, Z.N., Zhang, X.J., et al. (2013) Ultrathin, Mo-lecular-Sieving Graphene Oxide Membranes for Selective Hydrogen Separation. Science, 342, 95-98.
https://doi.org/10.1126/science.1236686
[26] Kim, W.G. and Nair, S. (2013) Membranes from Nanoporous 1D and 2D Materials: A Review of Opportunities, Developments, and Challenges. Chemical Engineering Science, 104, 908-924.
https://doi.org/10.1016/j.ces.2013.09.047
[27] Peng, Y., Li, Y., Ban, Y., et al. (2014) Metal-Organic Framework Nanosheets as Building Blocks for Molecular Sieving Membranes. Science, 346, 1356-1359.
https://doi.org/10.1126/science.1254227
[28] Peng, Y., Li, Y., Ban, Y., et al. (2017) Two-Dimensional Met-al-Organic Framework Nanosheets for Membrane-Based Gas Separation. Angewandte Chemie International Edition, 56, 9757-9761.
https://doi.org/10.1002/anie.201703959
[29] Zhong, Z., Yao, J., Chen, R., et al. (2015) Oriented Two-Dimensional Zeolitic Imidazolate Framework-L Membranes and Their Gas Permeation Properties. Journal of Materials Chemistry A, 3, 15715-15722.
https://doi.org/10.1039/C5TA03707G
[30] Jiang, Y., Ryu, G.H., Joo, S.H., et al. (2017) Porous Two-Dimensional Monolayer Metal-Organic Framework Material and Its Use for the Size-Selective Separation of Nanoparticles. ACS Applied Materials & Interfaces, 9, 28107-28116.
https://doi.org/10.1021/acsami.7b10228
[31] Ying, Y., Liu, D., Ma, J., et al. (2016) A GO-Assisted Method for the Preparation of Ultrathin Covalent Organic Framework Membranes for Gas Separation. Journal of Materials Chem-istry A, 4, 13444-13449.
https://doi.org/10.1039/C6TA04579K
[32] Morigami, Y., Kondo, M., Abe, J., et al. (2001) The First Large-Scale Pervaporation Plant Using Tubular-Type Module with Zeolite NaA Membrane. Separation & Purification Technology, 25, 251-260.
https://doi.org/10.1016/S1383-5866(01)00109-5
[33] Caro, J. and Noack, M. (2008) Zeolite Membranes-Recent Developments and Progress. Microporous & Mesoporous Materials, 115, 215-233.
https://doi.org/10.1016/j.micromeso.2008.03.008
[34] Lai, Z., Bonilla, G., Diaz, I., et al. (2003) Microstructural Optimization of a Zeolite Membrane for Organic Vapor Separation. Science, 300, 456-460.
[35] Choi, M., Na, K., Kim, J., et al. (2009) Stable Single-Unit-Cell Nanosheets of Zeolite MFI as Active and Long-Lived Catalysts. Nature, 40, 246-252.
https://doi.org/10.1038/nature08288
[36] Varoon, K., Zhang, X., Elyassi, B., et al. (2011) Dispersible Exfoliated Zeolite Nanosheets and Their Application as a Selective Membrane. Science, 334, 72-75.
https://doi.org/10.1126/science.1208891
[37] Jeon, M., Kim, D., Kumar, P., et al. (2017) Ultra-Selective High-Flux Membranes from Directly Synthesized Zeolite Nanosheets. Nature, 543, 690-694.
https://doi.org/10.1038/nature21421
[38] Choi, J., Jeong, H.K., Snyder, M.A., et al. (2009) Grain Boundary De-fect Elimination in a Zeolite Membrane by Rapid Thermal Processing. Science, 325, 590-593.
https://doi.org/10.1126/science.1176095
[39] Zhang, H., Xiao, Q., Guo, X., et al. (2016) Open-Pore Two-Dimensional MFI Zeolite Nanosheet for the Fabrication of Hydrocarbon-Isomer-Selective Membranes on Porous Polymer Supports. Angewandte Chemie International Edition, 55, 7184-7187.
https://doi.org/10.1002/anie.201601135
[40] Agrawal, K., Topuz, B., Phan, T., et al. (2015) Oriented MFI Membranes by Gel-Less Secondary Growth of Sub-100 nm MFI-Nanosheet Seed Layers. Advanced Materials, 27, 3243-3249.
https://doi.org/10.1002/adma.201405893