Estimating the Interaction Energy of Asphaltene Aggregates with Aromatic Solvents

Zhang, Yan; Takanohashi, Toshimasa; Shishido, Takahiro; Sato, Shimio; Saito, Ikuo; Tanaka, Ryuzo

doi:10.1021/ef0498770

Cited by 23 publications

(25 citation statements)

References 29 publications

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“…24,25 In many cases, the models were successfully fit to the behavior of the mixtures. Solubility parameters have proven to be advantageous in averaging the properties of a solvent + an anti-solvent, e.g., heptane + toluene mixtures, once one or more additional fitting parameters are introduced.…”

Section: ■ Introductionmentioning

confidence: 99%

On the Applicability of the Regular Solution Theory to Asphaltene + Diluent Mixtures

Nikooyeh

Shaw

2012

Energy Fuels

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The similarity of the Hildebrand or Hansen solubility parameter is frequently used in petroleum science as a measure of the compatibility of constituents and for interpreting and correlating properties of asphaltene + diluent mixtures. A partial specific volume at near infinite dilution and enthalpies of solution are sensitive measures of solute−solvent interactions derived from high precision density and calorimetry measurements for dilute mixtures. In this contribution, the partial specific volumes and enthalpies of solution of pyrene and various Athabasca and Maya asphaltenes at near infinite dilution on a mole fraction basis, in decane, toluene, 1-methylnaphthalene, quinoline, anisole, 2,6-lutidine, pyridine, methylene chloride, and tetrahydrofuran are reported over the temperature range of 20−80°C. At 20°C, these diluents possess solubility parameters ranging from 15 MPa 0.5 (decane) to 22 MPa 0.5 (quinoline). The properties of pyrene + diluent mixtures are used to illustrate the application and misapplication of the regular solution theory to such mixtures. Thermodynamic measurements, partial specific volume, and enthalpy of solution are shown to be independent of both Hildebrand and Hansen solubility parameter values. These results do not support the use of the solubility parameter or other simple solution thermodynamic concepts to describe asphaltene + diluent mixture behavior. The need for a more detailed description of physiochemical phenomena arising upon mixing asphaltenes with diluents is discussed. ■ INTRODUCTIONRegular solution theory, as postulated by Hildebrand, is a modified version of van Laar's model for solutions. The theory assumes that the free-energy change upon mixing is correlated with the internal energy per unit volume of the species in the mixture and thereby makes predictions about the solubility behavior of materials. To apply regular solution theory, a mixture must meet the following criteria: 1 (1) components of the mixture should be subject to the same types of forces within the mixture as in pure liquids; (2) mutual energy (interactions) of two molecules should not depend upon their relative orientation or the presence of other molecules; (3) the distribution of molecules should be random; i.e., excess entropy of mixing is negligible; and (4) equilibrium relationships should be applicable to constituents collectively.Even though asphaltenes are defined as soluble in toluene, it is not clear whether asphaltene + diluent mixtures meet the above criteria because the operating definition for solubility of asphaltenes in toluene is based on macroscopic filtration measurements. 2 This definition is inconsistent with the thermodynamic definition of solubility of solids in liquids, which includes a phase change, from solid to liquid, for the solute followed by molecular-level dispersion in the solvent. Further, asphaltenes aggregate in organic media even at low concentrations. 3−8 There is a growing body of literature that asserts that asphaltenes can be separated from toluene by centri...

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Section: ■ Introductionmentioning

confidence: 99%

On the Applicability of the Regular Solution Theory to Asphaltene + Diluent Mixtures

Nikooyeh

Shaw

2012

Energy Fuels

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“…Extensive characterization of the aggregation behavior of these asphaltene samples has been reported previously, using small-angle neutron scattering measurements (SANS) , molecular dynamics simulation , small-angle x-ray scattering (SAXS) (Tanaka et al, 2004), differential scanning calorimetry (Zhang et al, 2005), and molecular-weight distribution analysis . The kinetic observations from the present study may be correlated to some aspects of the aggregation behavior, for example, SAXS analysis showed that the Khafji asphaltenes disaggregated at 179 • C, compared to 241 • C for Maya and 243 • C for Iranian Light.…”

Section: Selectivitymentioning

confidence: 99%

Dependence of Molecular Kinetics of Asphaltene Cracking on Chemical Composition

Rahmani

Gray

2007

Petroleum Science and Technology

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Asphaltenes from Iranian Light, Khafji and Maya were cracked in batch reactors at 350, 370, 390, 410, and 430 • C under hydrogen to produce liquid products for kinetic analysis. The cracking kinetics of the asphaltenes and their intermediates were analyzed on a total molar basis, to avoid the assumptions inherent in lumped kinetics. The overall reactivity of the three asphaltenes was similar for reaction times from 1 to 37 min. The behavior of Khafji was distinct in its initial high reactivity of sulfur species, while the high yield of hydrocarbon gases from Iranian Light was likely due to the poly-alkyl side chains of the aromatic rings. The apparent first order activation energies were in between 170 and 255 KJ/mol. The activation energies were in the sequence Iranian Light > Maya > Khafji.

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“…Typically, resin and asphaltene molecules tend to form association structures, which lead to crude oils with very high viscosity [14][15][16] . The major forces governing the resin and asphaltene aggregates formation are very complicated, including charge transfer, electrostatic interaction, van der Waals force, the acid-base interaction, hydrogen bonding, π -π interaction and coordination interaction [17][18][19][20] .…”

Section: Introductionmentioning

confidence: 99%