Effect of Primary Heavy Oil Processing on the Composition and Molecular Structure of Asphaltenes.

The changes in the molecular structure of asphaltenes during the primary processing of heavy oil are investigated. It is established that during withdrawal of the fractions before 350°C, the destruction and cleavage of saturated asphaltene fragments occur with a decrease in the content of naphthenic and paraffinic carbon by 5.5 and 1.7% rel. respectively. Reactions of recombination between the resulted macroradicals of asphaltene molecules contribute to an increase in their aromaticity factor by 7.2 rel % and the average MM by 190 a.m.u. The withdrawal of the fraction 350– 450°C results in a decrease in the average MM of asphaltenes by 425 a.m.u. with insignificant redistribution of carbon by various structural fragments. [ABSTRACT FROM AUTHOR]