Vapor Pressures and Thermophysical Properties of 1-Heptanol, 1-Octanol, 1-Nonanol, and 1-Decanol: Data Reconciliation and PC-SAFT Modeling

Abstract

Vapor pressures for liquid 1-heptanol (CAS RN: 111-70-6), 1-octanol (CAS RN: 111-87-5), 1-nonanol (CAS RN: 143-08-8), and 1-decanol (CAS RN: 112-30-1) were measured by a static method near ambient temperatures over an operating pressure range from 0.5 to 1270 Pa, thus complementing literature vapor pressure data obtained by ebulliometry at higher temperatures. Liquid heat capacities of 1-octanol, 1-nonanol, and 1-decanol were determined by Tian-Calvet calorimetry. Ideal-gas thermodynamic properties of 1-alkanols up to 1-heptanol were obtained by a combination of quantum chemistry and statistical mechanics and validated against available experimental data. Ideal-gas heat capacities and entropies for longer homologues were obtained by deriving a methylene increment due to having a too complex conformational shape for analogical treatment. The thermodynamic consistency of available data was validated by simultaneous correlation of selected vapor pressures, literature enthalpies of vaporization, and heat capacity differences between the ideal gaseous and the liquid phase. The results are represented by the Cox equation and compared with available literature data. Moreover, the results were used to examine the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state for its performance in describing vapor pressures, enthalpies of vaporization, residual liquid heat capacities, and liquid densities of neat 1-alkanols from 1-hexanol to 1-decanol. A new PC-SAFT parameter set for each of them was also regressed that improves the PC-SAFT performance for the studied properties in comparison to existing parameters published in the literature.