Molecular-Rotor-Enhanced Pore-Space Partition in Metal-Organic Frameworks for Boosting One-Step Ethylene Purification

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Science

Background:

• One-step ethylene purification from ternary acetylene/ethane/ethylene mixtures is a critical industrial challenge.
• Existing methods struggle to efficiently separate these components, limiting petrochemical process efficiency.

Purpose of the Study:

• To develop a novel strategy for synergistic optimization of metal-organic framework (MOF) pore environments.
• To enhance one-step ethylene separation from C2H2/C2H6/C2H4 mixtures using a molecular-rotor-enhanced pore-space partition (MR-enhanced PSP) approach.

Main Methods:

• Utilized pore partitioners inserted into MIL-88 framework open metal sites to tune pore apertures.
• Incorporated aromatic molecular rotors to regulate pore windows and enhance gas molecule interactions (π-π and C-H⋯π).
• Synthesized and tested optimized SNNU-636 adsorbent in fixed-bed breakthrough experiments.

Main Results:

• The optimized SNNU-636 adsorbent achieved a C2H2/C2H4 selectivity of 4.17, significantly outperforming counterparts without molecular rotors.
• Demonstrated preferential adsorption of C2H6 over C2H4.
• Enabled one-step production of ultrahigh-purity C2H4 (> 99.9999%) with a record yield of 7.8 mmol·g-1.

Conclusions:

• The MR-enhanced PSP strategy effectively optimizes MOF pore environments for superior ethylene separation.
• SNNU-636 adsorbent shows exceptional performance in one-step purification of ethylene from complex mixtures.
• The study provides a state-of-the-art solution for industrial ethylene purification challenges.