Solvent-free and one-pot synthesis of ultramicroporous carbons with ultrahigh nitrogen contents for sulfur dioxide capture

Recycling SO₂ from industrial tail gas is of great significance to control the environmental issues potentially induced by SO₂ emission. In the present work, porous carbons with rich ultramicropores and ultrahigh N contents (11.5–17.3 wt%) were synthesized by directly pyrolyzing the mixtures of glucose and urea at 700 ℃, without the use of any solvents. The synthesized porous carbons were characterized for porosity, morphology and elemental compositions, and also systematically investigated for SO₂ capture performance. It is found that the adsorption of SO₂ on synthesized porous carbons shows chemical behavior, owing to the strong acid-based interaction between SO₂ and pyridinic N. As consequence, the SO₂ capacities of synthesized porous carbons are very high, especially at low pressures (4.16 mmol/g at 296.2 K and 10 kPa). The synthesized porous carbons also display impressive adsorption selectivities for SO₂/CO₂/N₂ mixed gas, and good reversibility for SO₂ adsorption. Thus, it is believed that the synthesized porous carbons are promising candidates for selective and reversible SO₂ capture.