Improving methane storage on wet activated carbons at various amounts of water

Different mesoporous activated carbons were prepared by both chemical and physical activation processes and were examined for methane uptake in the presence of water. Methane isotherms were obtained at wet condition by wetting samples with water at mass ratio of water/carbon (R) close to 1.0. To compare, the amount of methane storage were also measured at dry situation. The maximum amount of methane stored was attained as 237 V/V at R=1.0 by hydrate formation at the methane critical pressure. In the next step, mass ratios of water/carbon were changed to investigate various amount of water for methane storage enhancement. Two other values of mass ratio of water/carbon (R=0.8 and 1.4) were selected and methane isotherms were obtained at the same conditions. Maximum values of 210 and 248 V/V were reached for methane storage, respectively. It was also observed that, in the pressure range lower than hydrate pressure, by increasing water ratio the hydrate formation pressure was decreased and methane uptake was much less than that of dry condition due to pore filling by water.