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 CH 4, 0–1.6 MPa for C 2 H 6, 0–0.3 MPa for C 3 H 8, and 0–0.05 MPa for C 4 H 10 . 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 C 4 H 10 > C 3 H 8 > C 2 H 6 > CH 4 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 C 4 H 10 > C 3 H 8 > C 2 H 6 > CH 4 .