Tricritical phenomena in asphaltene/aromatic hydrocarbon systems

Abstract

The calculation of phase behavior performed for asphaltene-micelles systems that assume several forms when they are mixed with petroleum fluid depending on its aromaticity, and on the relative sizes and polarities of the particles present in such fluid mixtures, is extended to tricritical phenomena. Asphaltene monomers form micelles in the presence of excess amounts of aromatic hydrocarbons and polar solvents, and they are dispersed in a petroleum fluid. The coupling between the micellization and phase separation may, in principle, lead to a near-tricritical coexistence of a monomer phase and a micellar phase; however, this tricritical phenomenon has not been experimentally observed. In this report, such tricritical phenomenon for asphaltene / aromatic systems is predicted.