The adsorption characteristics of helium under low temperature

Abstract

To study the separation of helium isotopes by cryogenic adsorption, figuring out the adsorption characteristics of helium isotopes at low temperature is necessary. In this paper, a cryogenic adsorption measurement device has been established. It consists of a cryostat with a GM Cryocooler as cold source, a Setaram gas sorption instrument and a temperature controller. The helium-4 adsorption isotherms were studied under different temperatures and pressures (15–300 K, 0–1.5 MPa) by volumetric method. The results showed that a little helium was adsorbed by activated carbon at 300 K and 77 K. The amount of adsorbed helium increased with the temperature decreased from 20 K to 15 K. At pressures lower than 0.2 bar, the adsorption capacity increased rapidly as the pressure increased. Besides, the isosteric heats of adsorption were obtained, which was around 515 J/mol and changed little. Moreover, the cryogenic adsorption results were analyzed by Langmuir model and Toth model.