Hydrodesulphurization of Thiophene: Iii. Adsorption of Reactants and Products on Chromia

The adsorption of thiophene, butene, hydrogen, and H2S on sulphided chromia was studied by a chromatographic method. Results were similar to those obtained earlier with a cobalt molybdate catalyst (P. J. Owens and C. H. Amberg, Advances in Chem. Ser. No. 33, 182 (1961)), showing strong interaction of the surface with H2 and H2S at reaction temperatures and weaker interaction with thiophene and butene. The main difference lay in the effect of adsorbed H2S on butene hydrogenation, the suppression being far less marked on chromia. Thiophene adsorption or product desorption are unlikely to be rate controlling in the desulphurization reaction, but neither hydrogen adsorption nor surface reaction could be ruled out as possible slow steps.