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Solvent effects on hydrodesulfurization of benzothiophene (BT) and dibenzothiophene (DBT) catalyzed by Co–Mo/Al2O3 were investigated under deep desulfurization conditions by using Langmuir-Hinshelwood (L–H) rate law. Solvents affected heats of adsorption of thiophenes rather than activation energy of HDS. Activation energies of HDS and heats of adsorption of thiophenes and solvents were estimated from the kinetic data.

In hydrodesulfurization of dibenzothiophene (DBT) catalyzed by supported ruthenium carbonylcesium hydroxide systems after presulfidation, the effects of various supports such as Al2O3, SiO2-Al2O3, SiO2, TiO2, NaY zeolite on the catalytic activity and product selectivity were investigated. In the absence of cesium, the conversion of DBT decreased in the order SiO2-Al2O3>Al2O3>TiO2>SiO2>NaY zeolite. When cesium hydroxide was added to the catalysts derived from supported Ru3(CO)12, the conversion of DBT increased remarkably with the use of Al2O3, SiO2-Al2O3, and SiO2 and reached the maximum values at Cs/Ru=2, 3 and 2, respectively. The conversion, however, decreased in the order Al2O3>SiO2>SiO2-Al2O3. Further addition of cesium decreased the activity. In contrast to this, when NaY zeolite was used, the conversion of DBT did not increase with the addition of cesium. For obtaining a high catalytic activity, it was essential to load the ruthenium hydride complex Cs[HRu3(CO)11], obtained after reacting Ru3(CO)12 with cesium hydroxide, onto the support.In the supported Ru3(CO)12-cesium hydroxide systems, biphenyl was produced selectively. XP spectra showed that the addition of an appropriate amount of cesium stabilized the ruthenium sulfide on the support even under hydrogen pressure.