Efficient SO₂ Capture Mediated via a Gradient Electric Field in Electron-Rich Conjugated Porous Aromatic Frameworks

Area of Science:

• Materials Science
• Environmental Chemistry
• Chemical Engineering

Background:

• Deep removal of sulfur dioxide (SO2) from flue gas is critical for environmental protection.
• Developing adsorbents with high SO2 uptake, selectivity, and stability remains a significant challenge.

Purpose of the Study:

• To prepare and investigate two novel porous aromatic frameworks (PAFs) for selective SO2 capture.
• To elucidate the mechanism behind the high SO2 adsorption performance of the synthesized PAFs.

Main Methods:

• Synthesis of porous aromatic frameworks (PAFs) with electron-rich conjugated structures.
• Static gas adsorption, dynamic breakthrough experiments, and stability tests.
• Molecular-level simulations using density functional theory (DFT).

Main Results:

• PAF-TrP and PAF-SBF exhibited high SO2 uptake capacities (259.1 and 344.7 cm3·g-1, respectively) at 298 K and 1 bar.
• Exceptional SO2/N2 selectivities were observed (e.g., 4159.3 for PAF-TrP).
• DFT calculations revealed that localized charge separation and gradient electric fields in PAFs induce strong interactions with SO2.

Conclusions:

• The synthesized PAFs demonstrate excellent performance for SO2 capture from flue gas.
• The electron-rich conjugated structures and resulting electric fields are key to the high selectivity.
• PAFs offer a promising pathway for developing stable and regenerable adsorbents for flue gas desulfurization.