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.