Phase equilibria of high molecular mass 1-alcohols in supercritical propane

The phase equilibria of high molecular mass 1-alcohols in supercritical propane is measured to investigate the relationship between the phase equilibrium pressure and the number of carbon atoms and by comparison with n-alkanes, to show the effect of the hydroxyl group. Binary phase equilibrium measurements of high molecular mass 1-alcohols (with 10, 12, 16, 18 and 22 carbon atoms) in supercritical propane are measured between 378 and 408 K for 1-alcohol mass fractions of 0.0175–0.600. Complete solubility below 100 bar, with no region of liquid–liquid immiscibility, is observed and the phase transition pressure increases with increasing number of carbon atoms. By plotting the number of carbon atoms as a function of the phase transition pressure at constant temperature and mass fraction 1-alcohol, a linear relationship is realized. This linear relationship can be used to estimate the phase equilibrium of 1-alcohols with 10–22 carbon atoms in propane. When the measured 1-alcohol–propane data is compared to published n-alkane–propane data it can be seen that the hydroxyl group has the effect of increasing the phase equilibrium pressure of the 1-alcohol in comparison to the n-alkane.