Adsorption Properties of N₂, CH₄, and CO₂ on Sulfur-Doped Microporous Carbons

A series of sulfur-doped microporous carbon materials were prepared by directly using potassium hydroxide as the activating agent. The specific surface area and pore volume of the sample CKS-5 (activated at 800 °C for 180 min according to an alkali/carbon ratio of 4:1) reached 2088 m 2 /g and 1.240 cm 3 /g, respectively. The adsorption isotherms of N 2, CH 4, and CO 2 on five samples were determined by a volumetric method to obtain insight into the relationship between adsorption performance and porosity. CSK-5 with a developed pore structure exhibited a higher adsorption amount of CO 2 and CH 4 at high pressure. For the selectivity, the CS sample presented the highest selectivity for CO 2 /CH 4, of which the selectivity of separation reached as high as 5.86. The highest selectivity of separation of CH 4 /N 2 (3.644) was present on CSK-7.