Estimation of Physical Properties of Vegetable Oils and Biodiesel using Group Contribution Methods

Most fatty acids, vegetable oils and fatty esters, especially those with long carbon chains, do not have all pure component physical properties described in the literature, relevant for design and analysis of chemical processes. One way to obtain these properties is to use estimation methods such as group contribution methods which need only the structural information of the molecule. In this study, eight pure component physical properties (boiling temperature, critical temperature, critical pressure, critical volume, Gibbs energy of formation, enthalpy of formation, acentric factor and liquid heat capacity) of twenty-two fatty acids (C-4 to C-20) and their corresponding methyl and ethyl esters, and eight vegetable oils and their respective biodiesels are considered. The performances of ten different methods are compared with respect to the eight pure component physical properties. Comparison among methods is made within available experimental data, indicating more reliable methods for estimating pure component physical properties and mixtures involving chemicals found in vegetable oils and biodiesel.