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Transformations of high-molecular-weight compounds of oil sand natural bitumen under the heat treatment were studied in this work. For that purpose the natural bitumen isolated from oil sand taken from the Beke field (Kazakhstan) was used as a substrate. Thermal processing of natural bitumen leads to a general change in the chemical composition of components and to an increase in the output of certain fractions. The contents of oil, tar and asphaltenes were determined and the elemental composition of tar-asphaltene compounds was evaluated. Molecular structures of the tar and asphaltene components of natural bitumen before and after cracking have been defined from the data of elemental analysis, NMR spectroscopy and molecular weight. The high molecular compounds were presented as giant molecules containing small aromatic islands some of which were linked by aliphatic chains, that was proved by infrared spectroscopy.

The analysis of the cracking products of bitumen Karmalskoye deposits (the content of fractions boiling up to 200 °C 6,7% wt.) has been performed. The influence of power plant coal ash microspheres on orientation of cracking bitumen components is stated. Bitumen cracking leads to significant yields of gas and coke for more than 20% wt. and destructions of all components. The initiated bitumen cracking in the presence of 10% microspheres at cracking temperature 450 °C leads to reduction of gas and coke yields and increase in fractions of ibp (initial boiling point) –360 °C at 10% wt. in comparison with products of the thermal bitumen cracking. The analysis of composition and amount of sulfur compounds in initial bitumen and the cracking products in the various conditions has shown that the thermal cracking leads to increased homologues benzothiophene contents due to partial destruction of resins, and to decrease in the content of homologues dibenzothiophene