Phase Equilibria in Systems of Naphthenates, Phenols, Toluene, and Water

Abstract

A partial phase diagram of the quaternary system based on 5‐phenylvalerate, 4‐pentylphenol, toluene, and water at 25°C has been performed, while keeping the ratio between 5‐phenylvalerate and 4‐pentylphenol constant. At a 1:1 weight ratio, a lamellar liquid crystalline phase exists close to the water‐surfactant/cosurfactant axis in the phase diagram. At low concentrations of surfactant/cosurfactant the region of existence is narrow, while upon increased concentration it becomes more extended against the oil corner of the phase diagram. By decreasing the amount of cosurfactant, the normal micellar and hexagonal phases are formed. Increasing the cosurfactant amount gives the reverse structures. The effect of adding polar resins extracted at pH 14 into the oil phase of the system was also investigated. All six different polar resins could be incorporated in the lamellar phase when the weight ratio between the surfactant and cosurfactant was 1:1. Addition of polar resins extracted from Fal 9, Bressay, and Heidrun crude oils reduces the lamellar phase, while addition of BP resins give no significant difference in the region of existence. On the other hand, adding polar resins extracted from Frade and Dalia crude oils increase the region of existence.

Keywords:

• Phase diagram
• lamellar phase
• surfactant
• cosurfactant
• polar resins
• naphthenate
• phenol

Acknowledgements

We would like to thank the industrial oil company consortium (JIP 1) for financial support. Funding from the Norwegian Research Council (Strategic Reorganization Program, SOP) is also gratefully acknowledged. We also thank Bodil Øvrevoll, Irune Indacoechea, and Vanesa Rojas for the preparation of the resins.