High-Connected Ternary Metal-Organic Framework Platform: Synthesis, Structure, and Methane Storage Capacity

Area of Science:

• Materials Science
• Chemistry
• Chemical Engineering

Background:

• High gravimetric and volumetric methane storage in a single metal-organic framework (MOF) is critical for natural gas vehicles.
• A trade-off typically exists between gravimetric and volumetric methane adsorption capacities in porous materials.

Purpose of the Study:

• To design and synthesize a novel MOF platform capable of simultaneous high gravimetric and volumetric methane storage.
• To overcome the inherent limitations in methane storage capacities of existing porous materials.

Main Methods:

• Synthesis of a novel pyridine-carboxylic acid ligand and combination with a trimeric iron cluster and dicarboxylic acid linkers.
• Construction of a 9-c ternary MOF platform using dual-solvent and dual-modulator solvothermal methods.
• Activation of MOFs via multistep solvent exchange and supercritical CO2 drying, followed by high-pressure methane adsorption tests.

Main Results:

• A series of MOFs with an ncb-type topological network and biporous hierarchy were successfully synthesized.
• Activated materials exhibited high porosity (pore volume > 1.90 cm³ g⁻¹), surface areas (gravimetric > 4800 m² g⁻¹, volumetric > 1600 m² cm⁻³).
• The Fe-ncb-TPDC-II MOF achieved exceptional methane storage working capacities of 0.533 g g⁻¹ (gravimetric) and 232 cm³ (STP) cm⁻³ (volumetric) at 273 K and 80 bar.

Conclusions:

• The developed MOF platform effectively addresses the gravimetric-volumetric trade-off for methane storage.
• The Fe-ncb-TPDC-II MOF demonstrates superior performance compared to other porous materials under similar conditions.
• This advancement holds significant potential for the practical application of natural gas as a vehicular fuel.