Comparative characteristics of insoluble products obtained by autoclave thermolysis of resins and asphsltenes from the Usinskaya oil

Abstract

The relevance of the research is caused by the fact that thermal destruction is one of the most common processes used to refine oil residues, heavy oils and natural bitumen. The use of such technologies promotes the formation of distillate fractions due to destruction of high-molecular components of feedstock and is always accompanied by the formation of oil-insoluble carbonization products, usually called coke. Some processes of oil refining are purposefully used to produce coke. Resin-asphaltene substances are considered as the main coke genes. Various options of resin and asphaltene thermal destruction are widely used to study their molecular structures. The study of the composition and properties of insoluble products obtained by thermal treatment of resin-asphaltene substances will provide information on the ways of their formation. The nature of insoluble products of resin and asphaltene thermal destruction at relatively low temperatures (160...250 °C) has not been studied yet. The main aim of the research is the comparative study of composition and properties of insoluble products obtained at different temperatures of autoclave thermolysis of resins and asphaltenes from the Usinskaya oil in an inert atmosphere. Objects: resins and asphaltenes of heavy, high-sulfur and highly resinous oil from the Usinskoye oil field, chloroform-insoluble products of their autoclave thermolysis in an argon atmosphere at 250, 450 and 650 °C. Methods: autoclave thermolysis in argon atmosphere, extraction, elemental analysis, IR and Raman spectroscopy, «Rock-Eval» pyrolytic analysis, flash pyrolysis (600 °C, 20 s) with «on-line» analysis of volatile products by gas chromatography with a mass+spectrometric detector. Results. The paper introduces the results on the study of insoluble products obtained at autoclave thermolysis of resins and asphaltenes from the Usinskaya oil in argon atmosphere at 160...650 °С. Chloroform-insoluble thermolysis products obtained with high yield from the resins of heavy high-sulfur oil at 250 °C significantly differ from the insoluble products obtained from resins and asphaltenes at 450 and 650 °C. By elemental composition, IR- and Raman spectra, the results of Rock Eval pyrolytic analysis and «on-line» flash pyrolys is (600 °C, 20 s) they correspond to «asphaltenelike» substances. Their formation is probably due to the breakage at 250 °C of the most labile S-S or C-S bonds in the resin molecules with generation and subsequent recombination of macroradicals. The thermal destruction of these sub-stances at higher temperatures (450 and 650 °C) is accompanied by formation of more carbonized coke-like products