Superhydrophobic Molecular Selector for Efficient Separation of Ethane over Ethylene under Dry and Humid Conditions
Mao Yi, Shan Wang, Shenfang Li, Shuo Zhang, Yilian Liu, Laiyu Zhang, Zifeng You, Xiong‐Li Liu, Lin Li, Junhua Wang, Hao Wang, Qiao Zhao, Baiyan Li, Xian‐He Bu
Abstract
Exploring humidity-resistant, ethane-selective adsorbents for the one-step purification of polymer-grade (>99.95%) ethylene from ethane-ethylene mixtures is of great importance, yet remains a significant challenge. To address this challenge, we present a novel strategy for constructing a “superhydrophobic molecular selector” (SMS) based on a porous organic cage (POC), which features a superhydrophobic outer surface and an inner cavity with multiple ethane-selective functional sites. The resulting SMS-POC-1 demonstrates excellent C 2 H 6 adsorption capacity (97 cm 3 g –1 at 298 K) and C 2 H 6 /C 2 H 4 selectivity ( S ads = 2.40 at 298 K), offering a superior trade-off between ethane adsorption capacity and C 2 H 6 /C 2 H 4 adsorption selectivity among all C 2 H 6 -selective adsorbents. Especially, breakthrough experiments demonstrate that SMS-POC-1 efficiently produces polymer-grade C 2 H 4 from C 2 H 6 /C 2 H 4 mixtures at 60% relative humidity (RH), making it the highest-selectivity adsorbent reported to date that can stably operate in a humid environment. The combination of experimental results and theoretical calculations reveals that the coexistence of a superhydrophobic outer surface and synergistic C–H···π interactions and hydrogen-bonding sites accounts for the high C 2 H 6 /C 2 H 4 separation performance under humid conditions for SMS-POC-1. Our work thus not only demonstrates a general strategy for guiding the design of humidity-resistant adsorption-separation materials but also presents a promising candidate for potential applications in hydrocarbon separation.