Carbon nanotube supported oriented metal organic framework membrane for effective ethylene/ethane separation.

Wei, Ruicong; Liu, Xiaowei; Zhou, Zongyao; Chen, Cailing; Yuan, Youyou; Li, Zhen; Li, Xiang; Dong, Xinglong et al. · Sci Adv · 2022

basic_science · Level V

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Abstract

Zeolitic imidazolate framework 8 (ZIF-8) is effective for C<sub>3</sub>H<sub>6</sub>/C<sub>3</sub>H<sub>8</sub> separation because of the "sieving effect" of a six-membered (6-M) window. Here, we demonstrate that ZIF-8 is a versatile material that could effectively separate C<sub>2</sub>H<sub>4</sub> from C<sub>2</sub>H<sub>6</sub> via its 4-M window along the <100> direction. We established a facile and environmentally friendly carbon nanotube (CNT)-induced oriented membrane (CNT-OM) approach to fabricate a {100}-oriented ZIF-8 membrane (100-M). In this approach, 2-methyimidazole was anchored onto the CNT surface followed by 3-hour in situ growth in aqueous solution at room temperature. The obtained 100-M, whose 4-M window is aligned along the transport pathway, showed ~3 times higher C<sub>2</sub>H<sub>4</sub>/C<sub>2</sub>H<sub>6</sub> selectivity than a randomly oriented membrane. Thus, this work demonstrates that the membrane orientation plays an important role in tuning selectivity toward different gas pairs. Furthermore, 100-M exhibited excellent mechanical stability that could sustain the separation performance after bending at a curvature of ~109 m<sup>-1</sup>.