Affiliation:
1. Institute of General and Inorganic Chemistry of the National Academy of Sciences of Belarus
Abstract
A detailed study of the supramolecular structure of high molecular weight resinous-asphaltene substances (RAS) and the study of their stability to thermal-oxidative degradation processes in the presence of surfactants is a promising scientific direction and can become the basis for the development of additional oil treatment processes and, as a result, the intensification of thermal transformations of oil dispersed systems (ODS). In the work it has been established that the maximum modifying effect, which consists in reducing the amount of asphaltenes by 8–11 % and increasing the concentration of resins, saturated and aromatic hydrocarbons in the composition of the dispersion medium, is achieved by the interaction of ODS with octadecylpropylenediamine, alkyldiamine with the content of ethoxylated groups n = 3–6 and butyl coconut fatty alcohol ester with n = 10. This fact is due to a change in the geometric parameters of asphaltene nanoaggregates due to the adsorption of these surfactants on their surface. Thus, against the background of an increase in the interplanar distances of condensed aromatic layers dm from 3.66 to 3.85 Å and values of the intrachain distance from 5.71 to 5.80 Å, the average diameter of aromatic layers decreases by 0.67–2.36 Å and the average height of their pack by 1.52–2.64 Å, while the average number of layers in a pack is 5. Estimation of the results of thermal analysis indicates that the RAS thermograms have a similar form with three endoeffects with minima in the ranges of ~ 34.7–37.7 °C (I); 325.7–339.3 (II) and 434.8–438.7 °С (III) and one exoeffect with a maximum of ~ 460.5–475.3 °С (IV). With a decrease in the factor of crystallinity and aromaticity of RAS, their resistance to the processes of thermo-oxidative degradation in the temperature region of coke formation increases. The energy of thermal-oxidative destruction for modified systems by surfactants exceeds by 21.6 kJ/mol of this indicator for unmodified RAS and is 62.07 ÷ 66.13 kJ/mol.
Publisher
Publishing House Belorusskaya Nauka
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