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Sites Characterization on Model Ruthenium Sulphide

1993; Elsevier BV; Linguagem: Inglês

10.1016/s0167-2991(08)64041-0

2542-6613

Michel Lacroix, C. Mirodatos, M. Breysse, T. Décamp, Shijie Yuan,

Catalysis and Hydrodesulfurization Studies

This work reports a systematic study of the changes in the catalytic activities and in adsorptive properties of ruthenium sulphide with sulphur removal. From physicochemical characterization of the reduced samples it is shown that 50% of the initial sulphur content can be eliminated without changing the structure and the morphology of the pyrite phase. The adsorption of CO, NO and H2S increases with the degree of reduction of the solid. However, the maximum of adsorption capacities for these probe molecules does not correspond to the maximum of catalytic activity observed for the reactions of H2-D2 exchange and 1-butene hydrogenation. This suggests that distinct sites are required for adsorption and for catalysis. The use of ammonia as probe molecule seems to be a good tool for determining the Brönsted acidic surface sites. From thermoflash desorption of hydrogen, it has been demonstrated that two different species are retained by the catalyst: one adsorbed on surface sulphur atoms and the other one adsorbed on coordinatively unsaturated ruthenium cation. The concentration of the latter correlates fairly well with the catalytic activities.