Methane adsorption on the graphene sheets, activated carbon and carbon black

Behavior of methane adsorption on typical carbon based materials was comparatively studied for development of storage medium for adsorbed natural gas (ANG). Three kinds of carbon materials, graphene sheets (GS), activated carbon and carbon black, which respectively has a specific surface area about 300 m2/g, 1118 m2/g and 76 m2/g, were selected for adsorption equilibrium testes within temperature-pressure range from 253.15 K to 293.15 K and 0 to 8 MPa. Langmuir-Freundlich (L-F) equation and a lattice theory based adsorption model were employed to determine the isosteric heat of adsorption and the molecular interaction energy between adsorbates. It is found that mean relative deviations between the experimental results and those predicted by L-F equation are less than 1%, and an adsorbent having a larger specific surface area has a higher adsorption amount and a bigger isosteric heat of adsorption. It is also noted that molecular energy among methane molecules within the adsorption layer on the carbon black is the largest in comparing with those on the GS and the activated carbon. Results also reveal that interaction mechanism between methane and the activated carbon is similar to that between methane and the GS. It suggests that the GS-related storage medium for ANG should have a higher specific surface area.