Supramolecular organic frameworks (SOFs) membrane with ultra-high hydrogen permeability for hydrogen purification: Microstructural design of JLU-SOF2

Simulating results showed that JLU-SOF2 has ultra-high hydrogen permeability (0.696 x 106 GPU) but low selectivity (7.46). Given the good structural designability of JLU-SOF2, it is valuable to develop the structure design of JLU-SOF2 for on-site hydrogen purification to improve selectivity and maintain high H2 permeability. In this study, the functional groups of JLU-SOF2 were modified to construct 13 membrane materials containing functional groups of different lengths. The effect of membrane materials modified with each functional group on hydrogen permeability and selectivity in mixed gases (CO2, CO, and H2) was investigated from a microscopic point of view utilizing molecular simulations. Results showed that all 13 functional groups could improve the gas selectivity, especially the -SO3H, -OCH3, and -CH2NH2 modified JLU-SOF2 membrane materials, which can 100 % intercept CO2 and CO and maintain an excellent H2 permeability (0.54 x 106GPU), which exceeded the industry standard by nearly 105 times. Molecular motion behavior analysis showed that stretching direction and length of functional groups are the key factors leading to different membrane pore sizes and play a crucial role in affecting gas transport.