Sun Yanwei, Liu Yi, Caro Jürgen, Guo Xinwen, Song Chunshan, Liu Yi
State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Linggong Road No. 2, Ganjingzi District, Dalian, 116024, China.
Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover, Callinstrasse 3A, 30167, Hannover, Germany.
Angew Chem Int Ed Engl. 2018 Dec 3;57(49):16088-16093. doi: 10.1002/anie.201810088. Epub 2018 Nov 11.
Preferred-orientation control has significant impact on the separation performance of MOF membranes. Under most conditions the preferred orientation of MOF membranes is dominated by the Van der Drift mechanism of evolutionary growth selection so that the obtained orientation may not be optimized for practical application. In this study, highly c-oriented NH -MIL-125 membranes were prepared on porous α-alumina substrates by combining oriented seeding and controlled in-plane epitaxial growth. Dynamic air-liquid interface-assisted self-assembly of c-oriented NH -MIL-125(Ti) seed monolayers, the use of layered TiS as the metal precursor, and single-mode microwave heating were crucial in ensuring the preferred c-orientation while simultaneously suppressing undesired twin growth. Owing to reduced grain boundary defects, the prepared c-oriented membranes showed an ideal H /CO selectivity of 24.8, which was 6.1 times higher than that of their randomly oriented counterparts under similar operating conditions.
择优取向控制对MOF膜的分离性能有重大影响。在大多数情况下，MOF膜的择优取向由演化生长选择的范德漂移机制主导，因此所获得的取向可能无法针对实际应用进行优化。在本研究中，通过结合取向晶种法和可控的面内外延生长，在多孔α-氧化铝基底上制备了高度c取向的NH-MIL-125膜。c取向的NH-MIL-125(Ti)籽晶单层的动态气-液界面辅助自组装、使用层状TiS作为金属前驱体以及单模微波加热对于确保择优c取向同时抑制不期望的孪晶生长至关重要。由于晶界缺陷减少，所制备的c取向膜表现出理想的H₂/CO₂选择性24.8，在相似操作条件下比其随机取向的对应物高6.1倍。
