Adsorptive separation studies of ethane-methane and methane-nitrogen systems using mesoporous carbon

Adsorptive separations of C2H6/CH4 and CH4/N-2 binary mixtures are of paramount importance from the energy and environmental points of view. A mesoporous carbon adsorbent was synthesized using a soft template method and characterized with TEM, TGA, and nitrogen adsorption/desorption. Adsorption equilibrium and kinetics of C2H6, CH4, and N-2 on the mesoporous carbon adsorbent were determined at 278, 298, and 318 K and pressures up to 100 kPa. The adsorption capacities of C2H6 and CH4 on the mesoporous carbon adsorbent at 298 K and 100 kPa are 2.20 mmol/g and 1.05 mmol/g, respectively. Both are significantly higher than those of many adsorbents including pillared clays and ETS-10 at a similar condition. The equilibrium selectivities of C2H6/CH4 and CH4/N-2 at 298 K are 19.6 and 5.8, respectively. It was observed that the adsorption of C2H6, CH4, and N-2 gases on the carbon adsorbent was reversible with modest isosteric heats of adsorption, which implies that this carbon adsorbent can be easily regenerated in a cyclic adsorption process. These results suggest that the mesoporous carbon studied in this work is a promising alternative adsorbent for the separations of C2H6/CH4 and CH4/N-2 gas mixtures. (C) 2012 Elsevier Inc. All rights reserved.