Sulfur doped microporous carbons for CO2 adsorption

Sulfur doped carbons were prepared through physical activation of sulfur containing resorcinol-formaldehyde resins. The sulfur doping level depended on the sulfuric acid addition amount during the synthesis of the resin, it was also found that the increase of sulfur content caused the enlargement of pores. The CO2 adsorption tests were carried out at 273, 298 and 323 K, the influences of different activation conditions were investigated systematically. The adsorption amount at 1 bar reached 5.63, 3.69 and 2.33 mmol/g at 273, 298 and 323 K, respectively. The results also revealed that both sulfur doping and the porous characteristics had important influences on the CO2 uptake. The sulfur doped carbon also showed a high initial isosteric adsorption heat of 48.8 kJ/mol, which is higher than that of undoped carbon and close to that of nitrogen doped carbon. It was concluded that sulfur doping could significantly enhance the interaction strength between CO2 and carbon surface.