Experimental gas-solid adsorption measurements were made on the binary and ternary mixtures of H,S, CO,, and C,H, on H-mordenite molecular sieve zeolite at 30°C. The C, H, containing binaries and the ternary mixture exhibited nonideal behavior, as evidenced by the azeotropelike crossovers in the composition domains and by the peaks in the total amount adsorbed surface. The ternary data were successfully predicted with the activity coefficients calculated by the spreading-pressure-dependent equation. Models that neglect the spreading-pressure dependence can only qualitatively predict the nonidealities.

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 °C and at pressures up to 2000 kPa. A virial equation was used to correlate the experimental data and to calculate the isosteric heats of adsorption and the limiting heats of adsorption at zero loading. The adsorption isotherms of isobutane exhibit inflection points at loadings of 4−6 molecules/unit cell in a certain temperature range. This unusual adsorption behavior is attributed to adsorption of isobutane in different locations of the channel system.

At low temperature near the normal boiling point, computer simulations of adsorption of gases can be compared directly with experiment. However, for adsorptive gas separations in which the gas is adsorbed near or above its critical temperature, absolute simulation variables must be converted to excess variables for comparison with experiment. The conversion of absolute to excess variables requires the helium pore volume of the adsorbent. Lennard‐Jones potential parameters for helium gas molecules interacting with the oxygen atoms of silicalite are ϵ/k = 28.0 K and σ = 2.952 Å. The helium pore volume of silicalite is 0.175 cm3/g. Lennard‐Jones potential parameters derived for Ar‐O interactions in silicalite are ϵ/k = 93.0 K and σ = 3.335 Å. Density profiles for adsorption of argon in silicalite at 300 K show that the local density is highest in the middle of the channels where the gas‐solid potentials overlap.

No abstract

No abstract