Optimizing HostGuest Interaction Sites in Metal-Organic Frameworks for Benchmark One-Step Ethylene Purification

Area of Science:

• Materials Science
• Chemical Engineering
• Adsorption Science

Background:

• Purifying ethylene from ternary acetylene/ethylene/ethane mixtures is challenging due to ethylene's intermediate physicochemical properties.
• Existing methods struggle with selective adsorption of acetylene and ethane over ethylene in a single step.

Purpose of the Study:

• To develop a synergistic host-guest interaction strategy for metal-organic frameworks (MOFs) to achieve one-step purification of ethylene.
• To design robust MOFs capable of preferential adsorption of acetylene and ethane, while weakly binding ethylene.

Main Methods:

• Utilized a synergistic host-guest interaction strategy involving open metal sites (OMS) for acetylene and aromatic rings (AR) for ethane.
• Synthesized three conformational isomeric 8-connected [Fe3(μ3-O)(COO)6] trigonal prismatic trinuclear cluster-based MOFs (SNNU-705-α/β/γ) with amino groups.
• Employed breakthrough experiments, in situ FT-IR spectra, and DFT calculations to validate the adsorption strategy and performance.

Main Results:

• SNNU-705-α/β/γ MOFs demonstrated boosted affinity for acetylene and ethane, with the weakest binding for ethylene.
• SNNU-705-γ achieved the highest ethane uptake (6.13 mmol g⁻¹) among reported MOFs for one-step ethylene purification at 298 K and 1 atm.
• Breakthrough experiments yielded exceptional ethylene productivity (>99.9999% purity) of 7.07, 6.75, and 5.46 mmol g⁻¹ for SNNU-705-α/β/γ, surpassing existing adsorbents.

Conclusions:

• The proposed synergistic host-guest interaction strategy effectively enables one-step purification of ethylene from complex mixtures.
• The SNNU-705 MOFs exhibit remarkable adsorption performance and high selectivity, indicating significant potential for industrial applications.
• This work provides a promising new avenue for developing advanced adsorbents for industrial gas separation processes.