Collect. Czech. Chem. Commun. 1985, 50, 2159-2169

Non-stationary experiments on thiophene and tetrahydrothiophene hydrodesulphurization

Vladimír Morávek and Miloš Kraus

Institute of Chemical Process Fundamentals, Czechoslovak Academy of Sciences, 165 02 Prague 6-Suchdol


The reactions of tetrahydrothiophene and thiophene in hydrogen on sulphided Mo/Al2O3, Co-Mo/Al2O3, and Ni-W/Al2O3 catalysts have been studied using pulse-flow, stopped flow, and started flow techniques. The composition of the effluent from the reactor was analyzed after a perturbation and the observed response curves have been interpreted from the point of view of the reaction mechanism and influence of the promotor (Co) in the Co-Mo/Al2O3 catalyst. The results confirm that at least partial saturation of the thiophene ring is necessary for hydrodesulphurization and that at least one C-S bond is splitted by hydrogenolysis, the second one either by hydrogenolysis or by elimination. Cobalt increases the hydrogenolytic activity of molybdenum, in its absence the predominant reaction of tetrahydrothiophene is dehydrogenation to thiophene.