Comparative studies of CO2 and CH4 sorption on activated carbon in presence of water

The sorption behavior of CO2 and CH4 on activated carbon in the presence of water was comparatively studied. The equilibrium sorption data of CO2 and CH4 on an activated carbon with a wide pore-size distribution were collected at the temperature of hydrate formation in the presence of different amounts of water. Differently from methane, the sorption behavior of CO2 was remarkably affected by pore dimension of activated carbons no matter the carbon is wet or dry. It affects the isotherm shape and the molar ratio of water to the fixed CO2 in wet carbon. This effect of pore dimension and the difference in the sorption behavior between CO2 and CH4 were explained based on the possibility of condensation and dissolution. The enthalpy change was evaluated on the basis of the sorption data at different temperatures for the formation of CO2 and CH4 hydrates in the pore spaces of the tested carbon.