On Specific Partial Molar Volume of Asphaltenes in Organic Liquids and Their Solubility Parameters

Monday, November 8, 2010: 1:20 PM
Deer Valley I (Marriott Downtown)
Kasra Nikooyeh and John M. Shaw, Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada

Similarity of Hildebrand solubility parameter is frequently used in petroleum science, as a measure of compatibility of constituents and is commonly used for interpreting and correlating asphaltene-diluent interactions. Specific partial molar volume at near infinite dilution is a sensitive measure of solute-solvent interactions derived from high precision density measurements of dilute mixtures. It equals the partial molar volume of a solute divided by its molar mass, but is obtained directly from the density measurements without invoking a molar mass for the solute. Such a measurement is appropriate here because the mean molar mass of asphaltenes is not known a priori. In this contribution, the specific partial molar volumes of Athabasca and Maya heptane asphaltenes at near infinite dilution are reported for organic liquids over the temperature range 20 - 80 C. The organic liquids comprise pure compounds and binary mixtures including: heptane, toluene, 1-methylnaphthalene, quinoline, anisole, 2,6-lutidine, pyridine, methylene chloride, tetrahydrofuran, decane). At 20 C, these organic liquids possess solubility parameters ranging from 15 MPa0.5 (heptane) to 22 MPa0.5 (quinoline and methylene chloride). Surprisingly, the solubility parameter of the organic liquids, in this range, does not appear to correlate with the specific partial molar volume of these asphaltenes at near infinite dilution. Estimation of the solubility parameter of asphaltenes is discussed.

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