Pore Contraction in an Adenine-Based Metal-Organic Framework for Light Hydrocarbon Separation

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Controlling pore size is critical for designing effective porous frameworks for hydrocarbon separations.
• Metal-organic frameworks (MOFs) offer tunable structures for gas adsorption applications.
• Adenine-based MOFs present a promising platform for selective hydrocarbon adsorption.

Purpose of the Study:

• To synthesize and characterize a novel adenine-based metal-organic framework, Zn(pip)(ad).
• To investigate the effect of ligand modification on pore size and adsorption properties.
• To evaluate the framework's performance in separating hydrocarbon mixtures.

Main Methods:

• Synthesis of Zn(pip)(ad) using adenine (Had) and piperidine-4-carboxylic acid (Hpip) ligands.
• Characterization of the framework's structure and pore environment.
• Gas adsorption and dynamic breakthrough experiments for hydrocarbon mixture separation.

Main Results:

• The Zn(pip)(ad) framework exhibits preferential adsorption of heavier hydrocarbons (C3H8 > C2H6) over methane (CH4).
• Dynamic breakthrough experiments demonstrated stepwise separation of CH4/C2H6/C3H8 mixtures.
• High-purity methane was successfully isolated in the initial elution stage.

Conclusions:

• Replacing aromatic ligands with saturated amine carboxylates in adenine-based MOFs expands linker diversity.
• Subtle modification of pore size and environment enables selective hydrocarbon adsorption.
• This work offers new strategies for tuning MOF properties for efficient gas separations.