Adsorbent Helium Density Measurement and Its Effect on Adsorption Isotherms at High Pressure

Abstract

On the basis of an experimental study in a large temperature range, it is shown that “helium densities” of adsorbents measured at room temperature could be erroneous due to a non-negligible effect of helium adsorption. It is proposed that the density obtained with helium at high temperature, for instance, at the regeneration temperature of the adsorbent, be considered as the adsorbent density. Using the corrected densities of 3A, 4A, 5A, and 13X zeolites and of activated and graphitized carbons and of silica gel, we experimentally determined the adsorption of helium on the above mentioned adsorbents at room temperature and in a large pressure range up to 500 MPa. The shape of the adsorption isotherm reveals no saturation at high pressure. These experimental data are in agreement with Monte Carlo simulations of adsorption of a Lennard-Jones gas by a rigid plane as well as by a microporous rigid solid interface. We also examined implications of the new helium density of activated carbon for our previous mea...