Oyama S Ted, Aono Haruki, Takagaki Atsushi, Sugawara Takashi, Kikuchi Ryuji
College of Chemical Engineering, Fuzhou University, Fuzhou 350116, China.
Department of Chemical Systems Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Membranes (Basel). 2020 Mar 22;10(3):50. doi: 10.3390/membranes10030050.
Silica-based membranes prepared by chemical vapor deposition of tetraethylorthosilicate (TEOS) on γ-alumina overlayers are known to be effective for hydrogen separation and are attractive for membrane reactor applications for hydrogen-producing reactions. In this study, the synthesis of the membranes was improved by simplifying the deposition of the intermediate γ-alumina layers and by using the precursor, dimethyldimethoxysilane (DMDMOS). In the placement of the γ-alumina layers, earlier work in our laboratory employed four to five dipping-calcining cycles of boehmite sol precursors to produce high H selectivities, but this took considerable time. In the present study, only two cycles were needed, even for a macro-porous support, through the use of finer boehmite precursor particle sizes. Using the simplified fabrication process, silica-alumina composite membranes with H permeance > 10 mol m s Pa and H/N selectivity >100 were successfully synthesized. In addition, the use of the silica precursor, DMDMOS, further improved the H permeance without compromising the H/N selectivity. Pure DMDMOS membranes proved to be unstable against hydrothermal conditions, but the addition of aluminum tri-sec-butoxide (ATSB) improved the stability just like for conventional TEOS membranes.
通过在γ-氧化铝覆盖层上化学气相沉积原硅酸四乙酯（TEOS）制备的二氧化硅基膜，已知对氢气分离有效，并且对于用于制氢反应的膜反应器应用具有吸引力。在本研究中，通过简化中间γ-氧化铝层的沉积并使用前驱体二甲基二甲氧基硅烷（DMDMOS），改进了膜的合成。在γ-氧化铝层的放置方面，我们实验室早期的工作采用勃姆石溶胶前驱体进行四到五个浸渍-煅烧循环以产生高的氢气选择性，但这需要相当长的时间。在本研究中，即使对于大孔载体，通过使用更细的勃姆石前驱体颗粒尺寸，仅需要两个循环。使用简化的制造工艺，成功合成了氢气渗透率>10 mol m⁻² s⁻¹ Pa⁻¹且氢气/氮气选择性>100的二氧化硅-氧化铝复合膜。此外，二氧化硅前驱体DMDMOS的使用进一步提高了氢气渗透率，同时不影响氢气/氮气选择性。纯DMDMOS膜被证明对水热条件不稳定，但添加三仲丁醇铝（ATSB）像传统TEOS膜一样提高了稳定性。
