On the description of isotherms of CH4 and C2H4 adsorption on graphite from subcritical to supercritical conditions

Different potential models for methane and ethylene are tested for their suitability for the description of bulk phase behavior, including coexistence, and adsorption on a graphite surface under sub- and super-critical conditions using GCMC simulation. Under sub-critical conditions, those intermolecular potential models that describe correctly the vapor–liquid equilibria were found to be adequate for the description of surface adsorption. These potential models can also give a good account of adsorption under supercritical conditions or near-critical conditions, provided the experimental data (in terms of excess) are correctly obtained with the reliably determined void volume as illustrated in this paper with methane adsorption.