Deep Desulfurization with Record SO₂ Adsorption on the Metal-Organic Frameworks

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Selective sulfur dioxide (SO2) removal is critical for industrial processes like flue gas desulfurization and natural gas purification.
• Developing adsorbents with high SO2 capacity at low partial pressures and robust cycling stability presents a significant challenge.

Purpose of the Study:

• To develop novel isostructural gallate-based metal-organic frameworks (MOFs) for efficient and selective sulfur dioxide capture.
• To investigate the adsorption mechanisms, capacity, selectivity, and long-term stability of these MOFs for SO2 removal.

Main Methods:

• Synthesis of isostructural gallate-based MOFs.
• Gas adsorption isotherms and breakthrough experiments to evaluate SO2 uptake and selectivity.
• Dispersion-corrected density functional theory (DFT) calculations and single-crystal X-ray diffraction to elucidate adsorption mechanisms.
• Cyclic adsorption-desorption tests to assess material stability.

Main Results:

• Gallate-based MOFs exhibit abundant hydrogen bond donors for selective SO2 recognition and dense packing.
• Achieved ultrahigh SO2 adsorption uptake (6.13 mmol cm-3) at 0.002 bar on Co-gallate, surpassing existing MOFs.
• Demonstrated record-high selectivity for SO2/CO2 (325), SO2/N2 (>1.0 × 10^4), and SO2/CH4 (>1.0 × 10^4).
• MOFs maintained performance after five cycles, indicating excellent cycling stability.

Conclusions:

• The designed gallate-based MOFs offer a promising solution for efficient SO2 capture due to strong hydrogen bonding interactions and optimal pore structures.
• These materials exhibit superior performance in terms of capacity, selectivity, and stability for deep SO2 removal applications.