A Microporous Hydrogen-Bonded Organic Framework with Alkynyl Sites for Highly Efficient Propane/Propylene Separation
Yubo Wang, Yuxin Lin, Jia‐Xin Wang, Xu Zhang, Hui Wu, Wei Zhou, Banglin Chen, Guodong Qian, Bin Li
Abstract
Developing propane-selective adsorbents for propane/propene (C 3 H 8 /C 3 H 6 ) separation can energy-efficiently produce high-purity C 3 H 6, but it remains unexploited in porous hydrogen-bonded organic frameworks (HOFs) because of lacking effective C 3 H 8 binding sites. Reticular chemistry provides a powerful strategy for fine-tuning of pore size and functionality; however, this strategy is extremely challenging to be implemented in HOFs owing to the weak H-bonds with poor directionality. Herein, we report, for the first time, the implementation of a reticular chemistry strategy to design and synthesize a series of isoreticular HOFs (ZJU-HOF-59–ZJU-HOF-62) for achieving highly efficient C 3 H 8 /C 3 H 6 separation. Four isoreticular HOFs were constructed by four tetracarboxylic ligands, in which their pore sizes and functional sites are systematically engineered. These HOFs exhibit a tunable and gradually improved binding preference of C 3 H 8 over C 3 H 6 . Among them, ZJU-HOF-62 with abundant dialkynyl sites and suitable pore sizes demonstrates the fully inverse C 3 H 8 /C 3 H 6 separation, exhibiting the highest C 3 H 8 uptake (146.8 cm 3 g –1 ) and C 3 H 8 /C 3 H 6 selectivity (1.53) at 298 K and 1 bar. Theoretical calculations reveal that multiple dialkynyl and carboxylic sites provide stronger multipoint H-bonding and van der Waals interactions with C 3 H 8 than C 3 H 6 . The excellent separation capacity of ZJU-HOF-62 for actual C 3 H 8 /C 3 H 6 mixtures was proved by dynamic breakthrough experiments, providing a maximum C 3 H 6 productivity of 12.1 L kg –1 . This work opens the design of porous HOFs for challenging C 3 H 8 /C 3 H 6 separation.