Modulator-Tuned Cu(II) Metal-Organic Frameworks for Cooperative Sulfur Dioxide Capture

Area of Science:

• Materials Science
• Environmental Chemistry
• Chemical Engineering

Background:

• Sulfur dioxide (SO2) is a hazardous industrial pollutant requiring efficient capture for environmental protection and resource recovery.
• Conventional adsorbents struggle with selectivity and performance degradation in complex flue gas conditions, especially at high temperatures.

Purpose of the Study:

• To design and synthesize novel isostructural metal-organic frameworks (MOFs) for enhanced sulfur dioxide (SO2) capture.
• To investigate the impact of modulators on MOF adsorption performance, selectivity, and stability at elevated temperatures.

Main Methods:

• Construction of isostructural MOFs (Cu-L, Cu-L-FA, Cu-L-BA) using a pyrazine tetracarboxylate linker, copper ions, and formic/benzoic acid modulators.
• Characterization of MOF topology (4,4-connected mfj) and evaluation of SO2 adsorption capacity and performance retention at various temperatures and pressures.
• Mechanistic studies using computational and experimental approaches to elucidate SO2 adsorption pathways and interactions.

Main Results:

• The synthesized MOFs exhibit a rare 4,4-connected mfj topology and demonstrate substantial SO2 uptake capacity.
• The formate-modulated variant (Cu-L-FA) achieved 4.5 mmol·g-1 SO2 uptake at 298 K and 1 bar, retaining 97% capacity at 313 K.
• Modulators optimized adsorption-regeneration energy and induced SO2-specific dynamic interactions, enhancing cooperative adsorption.

Conclusions:

• Isostructural MOFs with retained modulators offer a novel strategy for designing high-performance SO2 adsorbents.
• The formate-modulated MOF (Cu-L-FA) shows superior SO2 capture capacity and stability in simulated flue gas conditions.
• This approach provides a pathway for developing advanced materials for efficient flue gas desulfurization and resource recovery.