Computer simulation of CO2/CH4 mixture adsorption in wet microporous carbons

Abstract

Adsorption of CH4, CO2 and their mixtures in dry and wet microporous carbons at 298 K is studied using grand canonical Monte Carlo computer simulations. Special attention is paid to the effects of water content and pore size on adsorption capacity and selectivity of the carbonaceous porous material. The presence of pre-adsorbed water may lead to non-monotonic dependence of adsorbed gas capacity on moisture content, which is observed for pure CO2 and CO2/CH4 mixtures at low adsorbate density (i.e., in wider pores, at low gas pressures, for low content of water). This effect is shown to be caused by electrostatic interactions of CO2 molecules with pre-adsorbed water. Under other conditions the presence of water in the pores leads to a decrease of the accessible volume causing a decrease of the adsorption capacity.