Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

The phase behavior of the supercritical CO2+1-alcohol homologous series for 1-octanol and higher alcohols is investigated. A literature survey revealed that sufficient data are available lower alcohols (1-decanol and lower) but data are limited for higher 1-alcohols. Data for CO2+1-dodecanol, CO2+1-tetradecanol and CO2+1-hexadecanol were thus measured using a visual static synthetic method for T = (313-353) K. Measured and literature data indicated that the phase transition pressures are very high (greater than 28 MPa) for CO2+1-decanol and higher alcohols in the mixture critical region. Additionally, a temperature inversion (increasing temperature leading to decreasing phase transition pressure) is present in the mixture critical region and is more pronounced in systems containing higher 1-alcohols. The temperature inversion is postulated to result from the formation of alcohol multimers due to hydrogen bonding between alcohol molecules. From the phase behavior data, and published upper critical end point and solid-liquid-liquid-vapor equilibria data, Type III phase behavior according to the classification of Scott and van Konynenburg is assigned to the systems CO2+1-octanol to CO2+1-tetradecanol. However, for higher alcohols additional investigations are required to assign a phase behavior type. This systematic study hopes to aid future thermodynamic modelling attempts to describe the complex phase behavior of CO2+1-alcohol systems.