A phase separation caused by the solubility of butane in 2-methylpropan-2-ol–water mixtures

Abstract

The solubility of butane and propane at a partial pressure of 101.3 kPa has been measured at 278–335 K in a solvent consisting of water and t-butyl alcohol (2-methylpropan-2-ol), of composition up to 0.08 mole fraction t-butyl alcohol. In the solvent, a phase separation occurs when butane gas dissolves into it at low temperatures, and over a wide composition range. Conditions for this separation have been identified and related to the high solubility of butane in the solvents at atmospheric pressure. The phenomenon is compared to conventional salting-out of non-electrolytes from water.