Cracking of Resinous-Asphaltene Extra-Heavy Oil Compounds on the Highly Developed Surface of a Coal Additive

Abstract

The paper presents the results of cracking of extra-heavy oil in the pore space of a coal additive in a nitrogen atmosphere and in a subcritical aqueous fluid at a temperature of 365°C and a pressure of 17 MPa. The coal additive consisted of an amorphous carbon phase forming a developed microporous structure. An analysis using scanning electron microscopy and adsorption porometry established that a vapor- air modification of the coal additive changes its surface relief and leads to the development of a micro- and mesopore structure. The intrapore space of the modified coal additive contains 38.6 vol % mesopores with a specific surface area of 172 m²/g. The final products of extra-heavy oil cracking with the proposed coal additive are characterized by an increase in the content of saturated and aromatic hydrocarbons, as well as by an almost complete absence of asphaltenes. The largest hydrocarbon yield was observed during extra-heavy oil cracking in a nitrogen atmosphere. In experiments, asphaltene conversion processes are observed due to the destruction of C–C, C–N, and C–O bonds with the formation of low-boiling compounds and high-carbon substances. The largest yield of aromatic hydrocarbons is observed during cracking in a subcritical aqueous fluid, with the yield of liquid products being reduced due to intensive gas formation. The hydrocarbon composition of gases is dominated by lower alkanes, which indicates the destruction of C–C bonds.