Highly Selective Separation of Benzene/Cyclohexane by Three-Dimensional Covalent Organic Framework with 8,8-Connected bcu Net Topology
Yu Zhao, Tsukasa Irie, Dan Wen, Haruna Mabuchi, Kohki Sasaki, Mika Nozaki, Rina Tomioka, Weidong Zhu, Saikat Das, Teng Ben, Yuichi Negishi
Abstract
Here, we report the discovery of the first (8,8)-connected three-dimensional (3D) covalent organic framework (COF), TUS-88, having bcu topology by linking an 8-connected D 4h -symmetric quadrangular prism node to an 8-connected D 2h -symmetric tetragonal prism node. Derived from the π-aromatic conjugated system of pyrene and the abundant aromatic phenyl rings composing the COF scaffold, which promotes stronger π ··· π interactions with aromatic benzene (Bz) molecules, a superlative Bz uptake of 464 cm 3 g –1 was achieved for TUS-88, coupled with exemplary cyclohexane (Cy) uptake of 224 cm 3 g –1 and ideal Bz/Cy selectivity of 2.07 which are the current benchmark. Breakthrough experiments accomplished using a Bz/Cy (1:1, v/v) mixture corroborated the preferential adsorption of Bz by the COF from the mixture to generate high-purity Cy with a significant time interval of 75.4 min g –1 and a record-setting Bz/Cy breakthrough selectivity of 2.46.