Highly Efficient Separation of Hexane Isomers by Rigid-Flexible Pyrazine-Pillar Ultramicroporous Metal–Organic Framework
Ting Wang, Liang Yu, Mao Ye, Chenghua Deng, En Lin, Yu Zhang, Kaiyuan Wang, Shubo Geng, Yao Chen, Peng Cheng, Zhihua Qiao, Hao Wang, Zhenjie Zhang
Abstract
Separating linear, monobranch, and dibranch alkanes is a pivotal process in the petrochemical industry. Herein, we present an ultramicroporous metal–organic framework (MOF) with a rigid-flexible structure. Single-component adsorption isotherms demonstrate that this MOF exhibited high capacities for hexane (nHEX) and 3-methylpentane (3MP), whereas excluding 2,2-dimethylbutane (22DMB), resulting in remarkable uptake ratios for nHEX/22DMB (19.2) and 3MP/22DMB (12.6) at 303 K, surpassing those of most reported MOFs. Breakthrough results with the nHEX/3MP/22DMB ternary mixture further validate its excellent separation performance and good reusability. Single-crystal structure data of MOF adsorbing gas molecules reveal that the outstanding performance can be ascribed to its suitable pore size and guest-induced flexibility, with an adaptive backbone triggered by nHEX and 3MP, leading to strong affinities for these molecules and precisely locating their positions within the framework.