AQUEOUS HIGH-TEMPERATURE CHEMISTRY OF CARBOCYCLES AND HETEROCYCLES .16. MODEL SULFUR-COMPOUNDS - A STUDY OF HYDROGEN-SULFIDE GENERATION

The aquathermolysis reactivity of nine organic sulfur compounds was investigated to determine their potential to generate hydrogen sulfide during the cyclic steam stimulation process to recover Cold Lake bitumen. Dioctyl sulfide, 1-decanethiol, didecyl disulfide, 1-naphthalenethiol, 1,1'-dinaphthyl sulfide, 1,1'-dinaphthyl disulfide, 1-naphthyl 1-octyl sulfide, tetrahydrothiophene, and thiophene were selected as model compounds and subjected to neutral, basic, and acidic aquathermolysis conditions at 250 and 300-degrees-C. Thiols, and thiols formed by cleavage of sulfides and disulfides, were found to be the source of H2S evolution. Aliphatic sulfides, in addition to their usual C-S bond cleavage, showed alpha,beta-C-C bond cleavage. Nontronite clay was found to catalyze all cleavages at 300-degrees-C and to catalyze aromatic sulfide isomerization. Tetrahydrothiophene and thiophene were inert under all the reaction conditions investigated. It is shown that there is a significant increase in H2S production as the temperature is raised from 250 to 300-degrees-C for all substrates and conditions. To minimize the escape of H2S to the atmosphere, the steam stimulation processes should be run at as low a temperature as possible.