Selective SF₆/N₂ Separation with High Uptake Under Low Pressures by Stable Al-MOF

Area of Science:

• Materials Science
• Environmental Chemistry
• Chemical Engineering

Background:

• Sulfur hexafluoride (SF₆) is a potent greenhouse gas requiring efficient capture and separation for emissions mitigation.
• Conventional SF₆ separation methods like distillation are energy-intensive and costly.
• Development of cost-effective and sustainable adsorbents is crucial for industrial SF₆ recovery.

Purpose of the Study:

• To develop a novel metal-organic framework (MOF) for efficient and economical capture of SF₆.
• To investigate the selective adsorption properties of MOF-303 for SF₆ over N₂.
• To evaluate the regeneration energy and overall cost-effectiveness of MOF-303 for industrial applications.

Main Methods:

• Synthesis of MOF-303 using earth-abundant aluminum and low-cost linkers.
• Characterization of MOF-303 pore size (8.3 Å) and its selective adsorption of SF₆ (5.5 Å) over N₂ (3.6 Å).
• Performance evaluation through breakthrough experiments under dynamic conditions and calculation of regeneration energy (22.9 kJ mol^-1).

Main Results:

• MOF-303 demonstrated benchmark SF₆ capture capacity (1.91 mmol g^-1 at P < 0.1 bar) with high selectivity (148).
• Low regeneration energy ensures practical and repeatable cycling of the adsorbent.
• Computational studies confirmed size-exclusive recognition mechanism driven by pore geometry.
• Cost analysis indicated >70% reduction compared to noble-metal adsorbents.

Conclusions:

• MOF-303 presents a highly selective and cost-effective adsorbent for SF₆ capture.
• The material's performance under dynamic conditions and low regeneration energy support its industrial viability.
• Rational pore engineering in MOFs offers a sustainable pathway for greenhouse gas mitigation and resource recovery.