GRAVIMETRIC MEASUREMENT OF BINARY GAS-ADSORPTION EQUILIBRIA OF METHANE-CARBON DIOXIDE MIXTURES ON ACTIVATED CARBON

Adsorption isotherms for the pure gases methane and carbon dioxide and their binary mixtures at constant gas composition have been determine d in a high pressure microbalance at 20, 40 and 60 degrees C and equil ibrium pressures up to 1.7 MPa on activated carbon. The gravimetric me thod proposed by Van Ness has been used to obtain the composition of t he adsorbed phase for the binary mixtures at 100 and 530 kPa. The idea l adsorbed solution (IAS) theory has been applied to predict the binar y adsorption equilibria from the single-component isotherms. The predi ctions of the IAS theory are only in moderate agreement with experimen tal data. The activity coefficients calculated for both components in the adsorbed phase are analogous to the respective vapour-liquid equil ibria positive deviations from Raoult's law. Finally, the real adsorbe d solution (RAS) theory has been used to fit the experimental data.