Transformations of Oil Asphaltenes in Supercritical Hexane

The conversion of oil asphaltenes of heavy oil in the supercritical hexane stream within the temperature ranges up to 250 and 250-450 degrees C and at pressure 5 MPa is investigated. Elemental analysis, IR and H-1 NMR spectroscopy and chromatography-mass spectrometry are used to characterize the initial asphaltenes and liquid products of their transformation. The C-14-C-27 n-alkanes, C-14-C-35 alkenes, C-27, C-29-C-35 hopanes and C-30 hopene, C-27-C-29 steranes, C-14-C-27 mono-, C-14-C-29 bi-, C-13-C-25 tri- and C-13-C-20 tetraalkylsubstituted benzenes, C-2-C-4 naphthalenes, C-2-biphenyls, C-0-C-3 phenanthrenes, C-1-C-2 fluorenes, C-0-C-1 pyrenes and C-0-C-1 fluorantenes, C-3-C-4 benzo-, and C-1-C-2 dibenzothiophenes were identified in the oils of a liquid product of the conversion of asphaltenes. The data obtained suggest the proceeding of reactions of dealkylation and cleavage of associative bonds in the course of thermolysis of asphaltenes in supercritical hexane.