Prediction of density and refractive index in furfural+lubricating oil systems

Abstract

Lubricating oil cuts are obtained by vacuum distillation of residues followed by a series of refining processes, such as aromatic removal. The aromatic content of vacuum distillates is reduced by solvent extraction, usually with furfural. Among the different properties of lubricating oils, density and refractive index are key to determine their final quality. In this work, density (D20) and refractive index (n20) at 20 °C of lubricating oil mixtures were determined from a pseudo-component characterization of the fluid using mixing rules. For that purpose, correlations between these properties and the average boiling point of the feedstock (T50%) were determined. These correlations were applied to different feedstock, thus obtaining the corresponding pseudo-component D20 and n20 values. Finally, D20 and n20 of the studied mixtures were calculated by using mixing rules relating pseudo-component properties and composition of samples.Obtained results were compared to those determined by a variety of methods in order to check the reliability of pseudo-component approach. Comparison of D20 predictions show that pseudo-component mixing rule exhibits similar accuracy as the best of the methods tested for the studied lubricating oil mixtures. Regarding to n20 predictions, the use of a function of refractive index as pseudo-component property, instead of refractive index, clearly improves the prediction accuracy. This modification yields deviations similar to those obtained by the most accurate of the methods tested for the analyzed lubricating oil mixtures. Pseudo-component approach presents as main advantage over tested correlations, that experimental information on refractive index or density are not required.