Mixed Desorption of He, H2, and CH4 Adsorbed on Charcoal Maximally Cooled at 10 K

Desorption rates of mixtures of He, H2, and CH4 adsorbed on activated carbon placed in an enclosed vessel are determined under the condition where the temperature is elevated from 10K to room temperature. Activated carbon is selected because of its good adsorption performance at the cryogenic temperature. The carbon used in the present study is covered with mesopores or micropores from 1 to 10 nm in diameter. The adsorption and desorption of their respective gases proceed independently, and the desorption behavior of each component is well expressed in terms of a Langmuir-Freundlich isotherm. Since desorption curves under different heating conditions can be correlated to the same one on a (T-pt) plot, it is considered that gas desorption proceeds under equilibrium condition between the adsorbent and gaseous phases. Two- or three-component desorption of He, H2, and CH4 from activated carbon can be described using an extended multicomponent Langmuir-Freundlich isotherm without any correction. Desorption curves calculated for their respective gases are in comparatively good agreement with experimental data.