Application of an amino-functionalized MIL-53(Al) MOF as an efficient, selective, and durable adsorbent for SO2 removal

Sulfur dioxide (SO2) is one of the acidic components found in the flue gas that can harm industrial facilities and the environment. SO2 adsorption by metal-organic frameworks (MOFs) is an emerging method to effectively remove SO2 in low concentrations from the gas mixtures. In this study, amino-functionalized MIL-53(Al), i.e., NH2-MIL-53(Al), was synthesized through the solvothermal method and examined for SO2 adsorption at relatively moderate pressure and temperature (up to 2 bar, 25–80 ℃). According to the results of XRD, FT-IR, TGA, and DSC analysis, NH2-MIL-53(Al) demonstrated appropriate water, acid, and thermal stability. The SO2 adsorption capacity of NH2-MIL-53(Al) was 5.21 mmol.g−1 at T = 25 °C and P = 0.92 bar, significantly higher than its CO2 adsorption capacity under similar conditions, demonstrating its high selectivity for adsorption of SO2 relative to CO2. Though the crystal structure of the tested MOF slightly changed after five adsorption/desorption cycles, its SO2 adsorption capacity decreased only 6.64%, signifying its proper durability and regenerability under humid and acidic conditions. These features are promising to use NH2-MIL-53(Al) as a suitable adsorbent to selectively remove SO2 from flue gas.