One-dimensional methane gas in the pores of ferrierite and Kihara's core potential

Abstract

The adsorption of methane on ferrierite has been measured at pressures 10⁻¹–10⁵ Pa and temperatures 130–300 K. The adsorbed methane molecules behave as a one-dimensional fluid and are freely rotating in the pores of ferrierite. The virial coefficients and their temperature dependences were determined up to the fourth coefficient. The observed second virial coefficient and its temperature dependence show that the quantum three-body effect plays an important role and Kihara's core potential can explain the results better than the Lennard-Jones potential. The heat of adsorption of methane is larger than that of Kr, though the boiling points are in the reverse order. This anomaly is discussed in terms of mutual interaction potentials and a three-body effect. Additionally, it was shown that N₂ and CO molecules, having a large electric quadrupole and dipole, respectively, are trapped on the pore wall at lower coverage regions and detailed analysis of their isotherms is difficult.