Enhanced Carbon Dioxide Capture from Diluted Streams with Functionalized Metal-Organic Frameworks

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Diluted carbon dioxide (CO2) streams, like flue gas from natural gas combustion, pose environmental challenges.
• Developing efficient and recyclable sorbent materials is crucial for carbon capture technologies.

Purpose of the Study:

• To synthesize and evaluate novel porous metal-organic frameworks (MOFs) functionalized with Lewis basic groups for CO2 capture.
• To investigate the impact of pore functionalization on CO2 adsorption capacity and selectivity under humid conditions.

Main Methods:

• Synthesis of aluminum 1,2,4,5-tetrakis(4-carboxylatophenyl) benzene (Al-TCPB) and two novel isostructural MOFs, Al-TCPB(OH) and Al-TCPB(NH2).
• Characterization using single-component adsorption isotherms and breakthrough experiments with humid gas mixtures (4/96 CO2/N2 at 75% RH).
• Analysis of material recyclability over multiple cycles and investigation of CO2/H2O interactions using solid-state nuclear magnetic resonance and density functional theory calculations.

Main Results:

• Functionalized MOFs exhibited significantly increased CO2 uptake compared to the parent material.
• Al-TCPB(OH) demonstrated the highest dynamic CO2 breakthrough capacity (0.52 mmol/g) under humid conditions.
• All synthesized MOFs showed excellent recyclability over eight humid breakthrough-regeneration cycles, with water molecules localizing near functional groups without hindering CO2 physisorption.

Conclusions:

• Pore functionalization of MOFs with Lewis basic groups enhances CO2 capture performance, particularly under humid conditions.
• The specific functional group and its interaction with water molecules influence CO2 adsorption behavior.
• These humidity-resistant, recyclable MOFs show significant potential as practical sorbent materials for industrial CO2 capture applications.