Abstract: Adsorption equilibria of CH4 and N2 on activated carbon and silica gel were measured for a
wide temperature range covering the critical point: 158-298 K for CH4, and 103-298 K for
N2. The determination of the compressibility factor is shown to have considerable effect on
isotherm behavior at conditions after the isotherm maximum. A change in adsorption
mechanisms on crossing the critical temperature was observed in all cases.The kind of
adsorbents and how far the equilibrium temperature to the critical one are major factors
affecting the transition of isotherms from sub- to supercritical. All continuous isotherms
can be modeled by a unique model for the supercritical region. The satisfactory fitting of
the model to the experimental isotherms proved the reliability of the absolute adsorption
determined by the proposed method.

Key words: adsorption, supercritical, methane, nitrogen

摘要： Adsorption equilibria of CH4 and N2 on activated carbon and silica gel were measured for a
wide temperature range covering the critical point: 158-298 K for CH4, and 103-298 K for
N2. The determination of the compressibility factor is shown to have considerable effect on
isotherm behavior at conditions after the isotherm maximum. A change in adsorption
mechanisms on crossing the critical temperature was observed in all cases.The kind of
adsorbents and how far the equilibrium temperature to the critical one are major factors
affecting the transition of isotherms from sub- to supercritical. All continuous isotherms
can be modeled by a unique model for the supercritical region. The satisfactory fitting of
the model to the experimental isotherms proved the reliability of the absolute adsorption
determined by the proposed method.

关键词: adsorption;supercritical;methane;nitrogen