Development of radioactive ^<35>S and ^3H pulse tracer methods-Elucidation of behaviors of sulfur and hydrogen on sulfided catalysts

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This research was supported by grants from the Ministry of Education, Science, Sports and Culture as Grant-in-Aid for Scientific Research (B) (2) with the project number 08455371 in the two years (1996-1997). This report summarized the study results on the structure of sulfided catalysts and the mechanism of deep hydrodesulfurization of a light gas oil using ^<35>S and ^3H radioisotope pulse tracer methods. Many basic point on the structure of HDS catalyst and the mechanism have still remained to be clarified although a number of studies on elucidation of HDS mechanisms using conventional characterization technique and the kinetic analysis method were reported. Especially, there have been few examples clarifying the behavior of sulfur on the working-catalyst. In order to develop the new catalysts continuously, it is essential to know in more detail the hydrodesulfurization mechanism. On the other hand, the tracer method has been considered to enable us quantify the behavior of sulfur o … More n the working catalyst and hydrogen behavior in the practical hydrodesulfurization reaction. Therefore, in this study, a ^<35>S and ^3H radioisotope pulse tracer method was developed and was applied to several aspects as follows : 1) Presulfidation mechanism of No-based desulfurization catalysts ; 2) Hydrodesulfurization kinetics of dibenzothiophenes on Mo-based catalysts ; 3) Retarding effect of H_2S and solvent on hydrodesulfurization reaction ; 4) Elucidation of sulfur mobility on Mo-based catalysts in hydrodesulfurization by ^<35>S pulse tracer method : 5) Deep desulfurization mechanism of light gas oil ; 6) Novel desulfurization catalysts using supported metal carbonyl complexes as catalytic precursors. From these studies, a lot of new information on the structure of sulfided catalysts, the insight of active sites and the mechanism of hydrodesulfurization was obtained. This makes us gain a good deal of enlightenment for development of new catalysts appropriated to the dep hydrodesulfurization of light gas oil. Less