ASPHALTENE SPREADING AND LIESEGANG RINGS

Eric Y. Sheu

(Presented by Dr. Yicheng Ling)

Vanton Research Laboratory, Inc., Lafayette, California, USA

Two-dimensional precipitation of ashaltene forms homogeneous film with wave-front fingering or well defined precipitated rings that resemble the Liesegang rings [1,2].  The kinetics of ring formation appears to be inward driven even through an outward flow is imposed.  Ratawi and Maya asphaltenes were tested at their critical concentrations near the flocculation point via adjusting toluene-heptane ratio.  Space low and time law that describe the Liesegang rings were adopted for interpretation of the asphaltene precipitation rings. The kinetics of evaporation of the solvent, the flocculation kinetics and the spreading surface are relevant to formation of the rings.  In the case of Ratawi vacuum resid asphaltene, uniform distribution of wave-front pearls were observed, in compatible with a theory proposed for Liesegang ring formation by Racz’s group [3]

[1] Liesegang, R.E., Naturwiss. Wochenschr. 11, 353 (1896)

[2] Fabricio Arteaga-Larios, Eric Y. Sheu, Elias Pérez, “Asphaltene Flocculation, Precipitation And Liesegang Ring” Energy & Fuel (2004)

[3] Antal, T, Droz, M, Magnin, J, and Racz, Z, Phys. Rev. Lett., 83, 2880 (1999)