ADSORPTION EQUILIBRIA OF C-1 TO C-4 ALKANES, CO2, AND SF6 ON SILICALITE

Adsorption isotherms of methane, ethane, propane, n-butane, isobutane, carbon dioxide, and sulfur hexafluoride were measured gravimetrically on silicalite crystals at temperatures ranging from 3 to 81 degrees C and at pressures up to 2000 kPa. A virial equation was used to correl ate the experimental data and to calculate the isosteric heats of adso rption and the limiting heats of adsorption at zero loading. The adsor ption isotherms of isobutane exhibit inflection points at loadings of 4-6 molecules/unit cell in a certain temperature range. This unusual a dsorption behavior is attributed to adsorption of isobutane in differe nt locations of the channel system.