Thermolytic Behavior of Crude Oil- and Natural Asphalt-derived Asphaltenes in the Presence of Several Aromatic Solvents.

Abstract

Thermolytic behavior of asphaltene fractions derived from both vacuum residue of Arabian crude oil and Indonesian natural asphalt was investigated. At first, the asphaltenes were analyzed by 1H- and 13C-NMR spectroscopy to obtain structural information. Structural differences between the two asphaltenes were found in the amount of naphthenic carbon and in the size of polycyclic aromatic units. The asphaltene obtained from Indonesian natural asphalt contains much larger amount of naphthenic carbon but smaller size of polycyclic aromatic units compared those from Arabian crude. Thermal treatments of the asphaltene were conducted in a glass tube at 420°C for 5min in the presence or in the absence of aromatic solvents. The molecular weight distribution of the samples and the products was evaluated by using a gel permeation chromatography. Among the solvents used, partially hydrogenated aromatic compounds such as 9, 10-dihydroanthracene (DHA) showed a slight effect on thermolysis of asphaltene, while polycyclic aromatic compounds such as anthracene (Ant) or acridine (Acr) were more effective. These results could be explained by referring to the radical acceptability of these aromatic solvents.