High-pressure liquid densities of fatty acid methyl esters: Measurement and prediction with PC-SAFT equation of state

In this work, experimental density data were reported for six fatty acid methyl esters , including methyl butyrate , methyl valerate , methyl caproate , methyl pelargonate , methyl heptanoate , and methyl caprylate . The densities were measured from 293.15 K to 363.15 K and pressures up to 60 MPa by a vibrating-tube densimeter . The relative uncertainty of the measurement is estimated less than 0.001 with a confidence level of 0.95. The high pressure densities were correlated with a Tait-type equation. The overall average relative deviation between experimental data and calculated results from Tait equation for the six fatty acid esters is 0.010%. The derived thermodynamic properties, such as isobaric thermal expansivity and isothermal compressibility , were obtained from the experimental density results. Additionally, for the studied esters, the molecular parameters of the PC-SAFT equation of state were obtained based on the corresponding vapor pressures and liquid densities. The PC-SAFT equation was used to predict the high pressure densities of the esters, and good agreements were observed.