One-dimensional rare gases in the pores of mordenite

Abstract

The adsorption of rare gases (argon, krypton, and xenon) on Na-mordenite has been measured and analysed. Entropies of admolecules, at lower coverages, were well described by a model of a mobile one-dimensional gas. The equation of state of admolecules is expressed in the virial form of the one-dimensional gas. Adsorption isotherms for argon and krypton were well described by equations containing up to the third virial coefficients, but those for xenon required the fourth. The second virial coefficients of the adsorbed gases showed a slight temperature dependence at higher temperature (220 < T/K < 330), while there was a steep increase with 1/T at lower temperature (140 < T/K < 220). The temperature dependence is discussed in terms of the difference between the sizes of the molecules and the pores of mordenite.