Составители:
32
2
nd
Mercosur Congress on
Chemical Engineering
4
th
Mercosur Congress on Process
Systems Engineering
A TRANSITION FROM MONOMERIC TO ASSOCIATED
ASPHALTENES IN CRUDE OIL SOLUTIONS
Igor N. Evdokimov
Department of Physics – Gubkin Russian State University of Oil and Gas
Abstract
It is widely recognized that physicochemical properties of crude oil
asphaltenes in processes of refining and processing (i.e. transfer
rates in catalyst’s porous networks) depend on their association
state in a hydrocarbonated environment. For various industrial
applications it is necessary to have a detailed knowledge of phys-
ico-chemical and structural properties of complex asphaltene col-
loids, in order to be able to master their behavior. We have studied
optical and dielectric properties (molar absorptivity, refractive in-
dex, dielectric constant, dielectric loss) in dilute toluene solutions
of Russian crude oils and of solid asphaltenes. Sharp inflections in
measured concentration dependencies are indicative of changes in
association states of asphaltenes. Apparently, asphaltenes may ex-
ist in a monomeric state only at concentrations below 1–2 mg/l,
while at 60–90 mg/l there is a demixing transition to a colloidal
system of asphaltene aggregates. By analysis of correlations be-
tween measured properties we expect to obtain quantitative infor-
mation on dipole moments of asphaltene monomers.
Keywords: Crude Oil, Asphaltenes, Associated State.
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