Highly Reversible and Selective Capture of Trace SO₂ in a Scalable Aluminum-Based Metal-Organic Framework

Area of Science:

• Materials Science
• Environmental Chemistry
• Chemical Engineering

Background:

• Effective flue gas desulfurization necessitates sorbents with selective and reversible sulfur dioxide (SO2) capture capabilities.
• Current high-performance materials often exhibit challenges in desorption and regeneration due to strong binding sites or narrow pores.

Purpose of the Study:

• To develop a robust and scalable sorbent for efficient trace SO2 capture and separation.
• To investigate the adsorption mechanisms and performance of MIL-120 for SO2 removal.

Main Methods:

• Utilized an aluminum-based metal-organic framework, MIL-120, for SO2 adsorption studies.
• Performed breakthrough experiments to evaluate SO2 capture in the presence of nitrogen dioxide (NO2).
• Employed direct visualization techniques to understand SO2 molecule interactions within the material.

Main Results:

• MIL-120 demonstrated exceptional SO2 uptake (2.1 mmol g-1 at 2500 ppm, 298 K) with optimal adsorption heats (19-42 kJ mol-1).
• Achieved fully reversible SO2 desorption at room temperature and a high SO2 packing density (1.92 g cm-3).
• Exhibited remarkable trace SO2 capture in the presence of NO2, with a record dynamic selectivity of 124 for SO2/NO2 mixtures.

Conclusions:

• MIL-120 presents a promising sorbent for reversible trace SO2 capture and separation from flue gas.
• The material's performance surpasses existing benchmarks, offering efficient SO2 removal and regeneration.
• Demonstrated potential for separating SO2/NO2 mixtures, crucial for environmental remediation.