Dual-Ligand-Engineered Ultramicroporous Porphyrinic MOF for Efficient C₂H₆/C₂H₄ and C₂H₂/CO₂ Separations

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Science

Background:

• Simultaneous separation of C2H6/C2H4 and C2H2/CO2 mixtures is challenging due to strict pore confinement and adsorption site requirements.
• Ultramicroporous metal-organic frameworks (MOFs) are crucial for selective gas adsorption and separation.

Purpose of the Study:

• To develop a novel dual-ligand engineered porphyrin-based framework for simultaneous C2 gas separations.
• To investigate the structure-property relationships governing the adsorption and separation performance of the designed MOF.

Main Methods:

• Synthesis of a dual-ligand MOF (Zn-TCPP-mtz) using Zn2+ nodes, TCPP, and mtz ligands.
• Gas adsorption isotherms and dynamic breakthrough experiments at 298 K and 1 bar.
• Density Functional Theory (DFT) calculations to elucidate adsorption mechanisms.

Main Results:

• Zn-TCPP-mtz exhibits 1D ultramicropores (7.2 × 4.8 Å2) with N/O functional sites and hydrophobic methyl groups.
• Achieved selectivities of 1.5 for C2H6/C2H4 and 3.1 for C2H2/CO2.
• Demonstrated one-step production of high-purity C2H4 (>99.9%) and C2H2 (>99.5%) with high productivities.

Conclusions:

• The dual-ligand strategy enables precise control over MOF pore architecture and adsorption environments.
• Zn-TCPP-mtz offers a promising platform for integrated C2 gas separation applications.
• The material's design facilitates selective adsorption through dispersion-dominated interactions within ultramicroporous channels.