Investigation of Physical Chemistry Properties of Asphaltenes Using Solubility Parameters of Asphaltenes and Their Fractions A1 and A2

Abstract

The Sphere method developed by Hansen (Hansen, C. M. Hansen Solubility Parameters: A User's Handbook; CRC Press: Boca Raton, FL, 1999) to calculate components of solubility parameters (SP), δ D , δ P , and δ H , where D, P, and H stand for dispersion, polar, and hydrogen bonding respectively, have been applied to resins, to asphaltenes, and fractions A1 and A2. Mean values for these compounds in MPa 0.5 were asphaltenes (19.5 ( 0.1, 4.7 ( 0.2, 4.2 ( 0.1); A2 (19.6 ( 0.1, 5.8 ( 0.1, 4.4 ( 0.2); A1 (20.9 ( 0.2, 5.6 ( 0.3, 6.8 ( 0.2); resins (18.6 ( 0.2, 3.6 ( 0.3, 3.2 ( 0.3). Also, the SP components of the asphaltene sample (AsH-NS), denuded from acidic natural surfactant (NS), were determined affording values equal to A2. These values were obtained after using 57 solvents, and the method is consistent with all known solubility properties of asphaltenes and confirm the expected solubility behavior of A1 and A2, with A1 being the less soluble material in all solvent examined. Excellent affinity between asphaltene with resins was predicted as well as affinity between samples examined. These results are coherent with a colloidal model whereby fraction A1 is in not contact with the solvent, being within a core shielded from the media by a periphery composed by fraction A2 and NS. Flocculation results measured in n-C 7 -1-methylnaphthalene mixtures correlate with the above SP showing the following order of flocculation tendency: A1 . A2 > asphaltenes (AsH). We also observed that flocculation points of A2 and AsH-NS were very close, and this strongly supports the colloidal model above. SP were helpful in analyzing other properties such as adsorption, vaporization, affinity, and molecular mass and paraffin's properties.

Effect of Precipitating Conditions on Asphaltene Properties and Aggregation

“…The last studied sample was one asphaltene enriched in resins, 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 solubility purposes. 57 A second interpretation, more alike to what was discussed in the preceding paragraphs, is provided by the works of Acevedo, Castillo and coworkers, 58,59 who showed that low solubility parameter asphaltenes fractions were found able to improve dissolution of "core asphaltenes" and modify their adsorptivity over solid surfaces. It is believed that low solubility parameter asphaltenes as described by …”

Solvent desorption of asphaltenes from solid surfaces

“…Several studies have dealt with determining the solubility parameters of asphaltenes mostly using the solubility sphere method based on experimental determination of the solubility or non-solubility of asphaltenes in various solvents with known solubility parameters [23][24][25] . By Fossen et al 26 used another method to determine the HSP for crude oils and SARA fractions including asphaltenes.…”

Development of a chromatographic methodology for the separation and quantification of V, Ni and S compounds in petroleum products

“…Solubility parameters have been demonstrated to have great potential to characterizethe solubility and other properties of petroleum and fossil solids and liquids both experimentally and theoretically [16][17][18][19]. Several authors have reportedthat the metallocompounds of V and Ni become separated from each other during the process of isolation with pyridine/water extracts [8].…”