Low-pressure solubilities of methane, ethane, propane, n-butane, isobutane, and hydrogen have been measured in n-hexadecane, n-eicosane, squalane, bicyclohexyl, octamethylcyclotetrasiloxane, diphenylmethane, and 1-methylnaphthalene over the temperature range 25' to 200OC. The accuracy of these measurements is better than 1%. The data for the hydrocarbon gases have been correlated with a generalized configurational entropy and a van Laar-type interaction parameter. The entropic component of that parameter is related to the free volume of the solvent as suggested by Flory's equation-of-state theory of fluid mixtures. The accuracy of the correlation is about -~l5oJ~.
SCOPESolubilities of gases in liquids are often required for efficient design of industrial processes. While reliable experimental data for gas solubilities are available for some common systems (Wilhelm and Battino, 1973;Battino and Clever, 1966), many systems of industrial interest have not been studied. Experimental data are particularly scarce at advanced temperatures and for solvents whose molecular size is large.The primary objective of this work is to provide accurate gas-solubility data for hydrocarbon gas-liquid systems in the temperature range 25O to 200OC. Using the apparatus described by Cukor (1971), new gas-solubility measurements in large-molecule solvents were made in the vicinity of 1 atm pressure. Equilibrium compositions, accurate to 1% or better, were determined from the measured total gas pressure and from a material balance.Presently available correlations for predicting gas solubilities in liquids are of limited accuracy, especially at advanced temperatures. The second objective of this work, therefore, is to investigate new methods for prediction of solubilities of gases in liquids over wide ranges of temperature. Particular attention is given to the effect on solubility of the size and shape of the solvent molecule, and of the solvent's free volume, as indicated by its coefficient of thermal expansion.
CONCLUSIONS AND SIGNIFICANCEGas solubilities expressed by Henry's constants are reported for 26 binary systems. The data were obtahed in the temperature range 2 5 O to 2OOOC and in the vicinity of 1 atm pressure. Their accuracy is estimated as better than 1%. The systems studied contain high-boiling hydrocarbon solvents for which gas-solubility data are rare.To correlate these and selected previously published solubility data, an expression for Henry's constant has been derived using a generalized configurational entropy (Staverman, 1950) and a residual term of the van Laar form. This residual contains both enthalpic and entropic contributions. At 300°K, the total residual term is correlated with the cohesive energy density of the solvent (corrected for molecular shape) and the entropic component of the residual term is correlated with the thermal expansion coefficient of the solvent. These correlations, coupled with an empirical assumption, give a good representation of the solubility data for hydrocarbon gases in the temperatur...
