Synthesis of Highly Active Ruthenium Sulfide Hydrodesulfurization Catalysts: Effect of Hydrogen in the Activation Process

In 1981 Pecoraro and Chianelli reported a complete study of catalytic behavior of transition metal sulfides catalysts in hydrodesulfurization (HDS) of dibenzothiophene (DBT) [1], in which was found a periodic tendency of the metallic sulfides activity, where ruthenium sulfide showed the highest HDS activity. These results were corroborated later by Raje et al. [2] and Liaw et al. [3], further studies coincided with the high catalytic activity of the ruthenium sulfide [4] superior to molybdenum traditional catalyst. Despite of Pecoraro results, the recent studies reported for ruthenium sulfide catalysts barely have achieved activities similar to those of industrial catalyst and only a few have reached the activity reported by Pecoraro [5]. Many authors related the low ruthenium sulfide catalytic activity with low sulfuration levels and remaining of metallic ruthenium in the catalyst, associated with the use during the activation process of hydrogen which is a reduction agent [6, 7, 8], nevertheless the role of metallic ruthenium in the HDS reaction is not clear.