The modulation of ethane-selective adsorption performance in series of bimetal PCN-250 metal-organic frameworks: Impact of metal composition

The developments of high-performance adsorbents have attracted ever-increasing attention in the separation of ethane/ethylene (C2H6/C2H4) mixtures. In this work, a series of ultra-stable C2H6-selective metal-organic frameworks (MOFs), PCN-250, and its bimetal version PCN-250(Fe2M2+, M2+ = Ni2+, Co2+, Zn2+, Mn2+), were synthesized to investigate the influence of metal compositions on the C2H6-selective performance. Among the five materials, at 298 K and 100 kPa, PCN-250(Fe2Co) showed the largest C2H6 uptake (6.21 mmol/g) while PCN-250(Fe2Zn) exhibited the highest C2H6/C2H4 ideal adsorption solution theory (IAST) selectivity (1.70). The molecular simulation revealed that the introduced metal ions have different influences on the atomic partial charge within the framework which varied the framework adsorption affinities toward C2H6/C2H4 molecules. Moreover, the research on PCN-250(Fe2Zn) suggested that the increased positive partial charge of metal sites together with a decreased charge density of benzene ring (BR) sites from the organic ligands will be beneficial to improve the desired C2H6 selectivity.

Automated summary

This study synthesized a series of highly stable metal-organic frameworks and investigated the influence of metal compositions on the C2H6 selective performance. Molecular simulation revealed that the introduced metal ions have different influences on the atomic partial charge within the framework, affecting the adsorption affinities toward C2H6/C2H4 molecules.