(480d) Responsive Porous Materials for Selective SO2 Capture from Flue Gas

Sulfur dioxide (SO₂) is harmful to human and environment, mainly produced by burning low-grade fossil fuels. The efficient removal of SO₂, especially for flue gas desulfurization (FGD) is of great significance and has attracted immense attention. Currently, the FGD processes are mainly accomplished by wet scrubbing using limestone slurry, but the method is energy-intensive and incapable to realize efficient removal of trace SO₂ (about 2000 ppm). In addition, the similar molecular size of SO₂ to other gases in flue gas, like N₂, CO₂, makes the SO₂ capture from flue gas be a great challenge. Herein, we report the discriminatively responsive behavior of SO₂ to other gases (e.g. CO₂, N₂) in the material with designed flexible pore structure. The material excludes the adsorption of N₂ and CH₄, and exhibits high SO₂/CO₂ (10/90) IAST selectivity, about 62.3 under ambient conditions. The binding domains for adsorbed SO₂ molecules and the binding energy are determined by single crystal X-ray diffraction experiments along with first-principles density functional theory calculations. The high-density host-guest interactions and guest-guest interactions between SO₂ molecules are responsible for the sensitive response of the material towards trace SO₂ (2000 ppm), and its SO₂ capture ability is further demonstrated by the breakthrough experiments. Moreover, the material is cheap and easy to scale up, making it be promising for trace SO₂ removal.