Rational Pore Design in Multivariate Metal-Organic Frameworks for C₂H₆/C₂H₄ Separation

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• The pore structure of metal-organic frameworks (MOFs) is critical for gas separation and adsorption.
• Controlling pore arrangement in MOFs influences their overall performance in separation applications.

Purpose of the Study:

• To investigate the effect of controlled pore arrangements in multivariate MOFs (MTV-MOFs) on gas separation efficiency.
• To compare the performance of core-shell MOF composites (CSMOFs) and mixed-linker MOFs (MLMOFs) in gas separation.

Main Methods:

• Synthesis of two types of MTV-MOFs: CSMOFs and MLMOFs, using ligands with differing bulkiness.
• Characterization of pore distribution in MLMOFs, revealing a gradual increase in bulky ligands from the center to the surface.
• Evaluation of gas separation performance using ideal adsorption solution theory (IAST) and breakthrough experiments.

Main Results:

• MLMOFs exhibit a high C2H6/C2H4 ideal adsorption solution theory (IAST) selectivity of 2.25.
• The distribution of alkoxy chains in MLMOFs creates multiple interaction sites, enhancing C2H6 adsorption.
• Breakthrough experiments demonstrated effective separation of C2H6/C2H4 mixtures with MLMOF, achieving high purity C2H4 (>99.9%) and productivity of 19.7 L kg-1 under dry conditions.

Conclusions:

• Pore space partitioning in MTV-MOFs is an effective strategy for optimizing gas separation performance.
• MLMOFs offer a promising route for efficient and selective separation of C2H6/C2H4 mixtures.
• The controlled pore architecture in MLMOFs is key to their enhanced gas separation capabilities.