Network engineering of a BTESE membrane for improved gas performance via a novel pH-swing method
Network engineering of a BTESE membrane for improved gas performance via a novel pH-swing method
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DOI：
10.1016/j.memsci.2016.03.060
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发表时间：
2016-08
影响因子：
9.5
通讯作者：
Xin‐Yao Yu;Li-Kai Meng;Takuya Niimi;Hiroki Nagasawa;M. Kanezashi;Tomohisa Yoshioka;T. Tsuru
中科院分区：
文献类型：
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作者：
Xin‐Yao Yu;Li-Kai Meng;Takuya Niimi;Hiroki Nagasawa;M. Kanezashi;Tomohisa Yoshioka;T. Tsuru
有机二氧化硅微孔膜由 1, 2-双（三乙氧基甲硅烷基）乙烷 (BTESE) 衍生溶胶制成，该溶胶在酸性 pH 条件下通过 pH 波动方法制备。该方法包括两个步骤，即向酸溶胶中添加特定量的NH3，并在反应几分钟后转变成酸。我们发现，通过 pH 变化产生的 BTESE 溶胶的尺寸可以通过 H2O/BTESE 摩尔比和碱中的反应时间来控制。在相同的 H2O/BTESE 比例为 60 的情况下，与酸法相比，pH 波动法制备的 BTESE 衍生溶胶显示出溶胶尺寸增加，并且溶胶尺寸很容易通过碱性 pH 中的主导反应（缩合反应）来控制。气体渗透结果表明，一些气体（He、H2、N2、C3H8、SF6）以大约两倍于使用酸性溶胶制备的膜（酸性膜）的速率渗透使用pH-摆动溶胶（pH-摆动膜）制备的膜； 200 °C 时，pH 摆动膜和酸性膜的 H2 渗透水平分别为 3.4×10−6 和 1.6×10−6mol m−2s−1Pa−1。 pH-swing 膜还保持了类似的 H2/C3H8 渗透率，范围为 2600~5800，这证实 pH-swing 处理是提高 BTESE 衍生有机硅膜气体渗透性的创新方法。造成这些结果的一个可能原因是使用 pH 波动溶胶制备的膜增加了溶胶的尺寸，从而减少了溶胶对中间层的渗透。此外，pH 波动引起的高交联提高了 BTESE 衍生的有机二氧化硅网络的热稳定性。在 50 °C 时，pH 摆动膜的 CO2/CH4 和 CO2/N2 渗透比分别高达 90 和 28。
Organosilica microporous membranes were fabricated from 1, 2-bis (triethoxysilyl) ethane (BTESE)-derived sols prepared in acidic pH via the pH-swing method. This method includes two steps whereby a specific amount of NH3was added into the acid sols and switched to acid after a reaction of several minutes. We found that the size of the BTESE-derived sols by pH-swing could be controlled via the H2O/BTESE molar ratio and the reaction time in alkali. Under the same H2O/BTESE ratio of 60, the BTESE-derived sols prepared in the pH-swing method showed an increase sol size in contrast with the acid method, and the sol size was easily controlled by the dominating reaction in alkali pH – the condensation reaction. Gas permeation results showed that some gases (He, H2, N2, C3H8, SF6) permeated the membrane that was prepared using the pH-swing sols (pH-swing membrane) at approximately twice the rate shown by the membrane prepared using acid sols (acid membrane); H2permeance levels of the pH-swing membrane and the acid membrane were 3.4×10−6and 1.6×10−6mol m−2s−1Pa−1at 200 °C, respectively. The pH-swing membrane also maintained similar H2/C3H8permeance ratios of ranging from 2600~5800, confirming that pH-swing processing is an innovative method for improvement in the gas permeance of BTESE-derived organosilica membranes. One possible reason for these results could be that the membranes prepared using the pH-swing sols increased the size of the sols, which reduced the sol penetration into the intermediate layer. Moreover, the high cross-linking that was caused by pH-swing increased the thermostability of the BTESE-derived organosilica networks. The CO2/CH4and CO2/N2permeance ratios for the pH-swing membrane were as high as 90 and 28, respectively, at 50 °C.