Calculation of the Kinetic Parameters for the Reactions of Formation and Decomposition of Thiophene Derivatives in the Process of High-Suifur Natural Bitumens Cracking

Cracking of high-sulfur natural bitumen of the Mordovo-Karmal and Ashalchi fields (Russia, Republic of Tatarstan) at a temperature of 450°C and different process times was studied. The characteristic features of the changes in the material and group compositions of the cracking products and the nature of the transformation of the group composition of the sulfur-containing compounds of oils as dependent on the cracking conditions were demonstrated. The kinetic regularities of the formation and decomposition of benzo- and dibenzothiophene derivatives in the cracking products of the natural bitumens were elucidated. Cracking was shown to involve breakdown of large molecules (resins and asphaltenes) with formation of a broad range of low-molecular-weight sulfur-containing compounds falling into oils. The sets of benzo- and dibenzothiophene homologs thereby formed were identical, but the rates of formation and decomposition of the sulfur-containing compounds were dependent on the thermal stability of the components of the initial bitumens. The data obtained provide a substantially better understanding of the laws governing the transformation of the sulfur-containing compounds of heavy hydrocarbon feedstock in thermal processes.