Adsorption separation of CO2, CH4, and N2 on microwave activated carbon

Abstract

In this study, the adsorption equilibrium isotherms of carbon dioxide, methane and nitrogen on microwave activated carbon (MAC) at three temperatures (298, 308 and 323K) have been obtained by a static volume instrument. The adsorption equilibrium data of CO2, CH4 and N2 at various temperatures were fitted to Langmuir and Toth isotherm models. It was found that the fitting results of Toth model were fine. The capacities of pure gas CO2, CH4 and N2 were 2.13, 0.98 and 0.33mmolg−1 at 298K and the partial pressure of 100kPa. The competition adsorption behavior of multi component was predicted by the extend Langmuir and Toth model. The results indicated that CO2 still dominate the adsorption system in the ternary mixtures. Additionally, the separation factors of the binary mixtures CO2/CH4, CO2/N2 and CH4/N2 were calculated from the isotherms data. The results showed that the separation factors (S) of different binary mixtures at 298K and the total pressure of 100kPa were as follows: CO2/N2 (14.6)>CO2/CH4 (4.37)>CH4/N2 (3.33). Finally, thermodynamic functions integral Gibbs’ free energy (ΔG), integral molar enthalpy change (ΔH) and entropy change (ΔS) were calculated to characterize adsorption behavior.