Adsorption Equilibria of C1-C4 from Natural Gas on Graphene Sheets

As a new kind of adsorbent, graphene sheets (GS) possess large surface areas and excellent adsorption properties. To investigate the adsorption equilibria of C1-C4 from natural gas on GS and fit the isotherms by the Langmuir Freundlich equation. GS were synthesized with a specific surface area of 805 m(2)/g and a specific pore volume of 1.03 cm(3)/g. The adsorption isotherms were measured using a volumetric method at five different temperatures between 263.15 and 303.15 K and at pressures of 0-6 MPa for CH4, 0-1.6 MPa for C2H6, 0-0.3 MPa for C3H8, and 0-0.05 MPa for C4H10. It was shown that, for all four hydrocarbons, the amount of adsorption decreased gradually as the temperature increased. The isotherms were described well by the Langmuir-Freundlich equation. The isosteric heat of adsorption values decreased in the order C4H10 > C3H8 > C2H6 > CH4 which was consistent with those of the extreme heats of adsorption. This suggests that the adsorption capacities of C1-C4 on GS decreased in the order C4H10 > C3H8 > C2H6 > CH4.