Phase equilibria of branched isomers of C10-alcohols and C10-alkanes in supercritical carbon dioxide

Phase equilibria data is presented for binary systems containing supercritical CO2 and C10-alcohol isomers (1-decanol, 2-decanol, 3,7-dimethyl-1-octanol, 2,6-dimethyl-2-octanol and 3,7-dimethyl-3-octanol) and C10-alkane isomers (n-decane, 2-methylnonane, 3-methylnonane and 4-methylnonane). The phase equilibria measurements were conducted at temperatures between 308 K and 348 K and compositions between 0.0153 and 0.697 mass fraction C10-compound. A temperature inversion is present for the CO2 + 1-decanol system, but was not observed for any other binary system in the temperature and composition ranges studied. The phase transition pressures of the binary systems containing the C10-alcohol isomers differed from one another and it is proposed that the solubility of the compounds are influenced by the hydroxyl group and the side branch positions. The phase transition pressures decreased in the following order: 1-decanol, 3,7-dimethyl-1-octanol, 2-decanol, 2,6-dimethyl-2-octanol and 3,7-dimethyl-3-octanol. No significant difference was observed between the phase behaviour of supercritical CO2 and n-decane and the phase behaviour of supercritical CO2 and the methyl-isomers of n-decane in the temperature and composition ranges studied.