Sorption/desorption equilibrium of methane in silica gel with pre-adsorption of water

The sorption/desorption equilibrium of methane onto/from silicon gel loading different quantity of water were measured with a volumetric method at 275 K for the pressure range of 0–11 MPa. The observed isotherms are similar to that for wet active carbons, and the quantity of the pre-adsorbed water showed a considerable influence on the sorption capacity. However, there is some difference in the variation trend of the sorption isotherms between the wet silica gel and the wet active carbon. Both pore size distribution and pore volume were changed after contacting water for different periods of time. Such changes might be caused by hydrolysis of the silicon-hydroxyl groups of the silicon surface and might be responsible for the peculiar behavior of isotherms observed at the wet silica gel.