STUDY OF HYDRODESULFURIZATION BY THE USE OF S-35 LABELED DIBENZOTHIOPHENE .2. BEHAVIOR OF SULFUR IN HDS, HDO, AND HDN ON SULFIDED MO AL2O3 CATALYST/

To investigate the behavior of sulfur during the hydrodesulfurization (HDS), S-35-labeled dibenzothiophene ([S-35]DBT) was reacted on a sulf ided Mo/Al2O3. It was found that S-35 in [S-35]DBT was accommodated on the catalyst and the concentration of S-35 On the catalyst always rea ched a steady state under fixed reaction conditions. S-35 accommodated os the catalyst cannot be removed without the incorporation of sulfur from HDS of sulfur compounds such as DBT, benzothiophene, thiophene, and thiophenol. The removal rate of S-35 from the catalyst depended up on the rate of HDS of these compounds, that is, the amount of sulfur i ncorporated into the catalyst. It was suggested that H2S is formed fro m some portion of sulfur on the surface of the catalyst other than fro m that in the sulfur compounds. When hydrodenitrogenation (HDN) and hy drodeoxygenation (HDO) reactions were carried out on the-catalyst cont aining S-35, some portion of S-35 could be replaced by oxygen atoms an d released as [S-35]H2S; in contrast to this, S-35 was hardly replaced by N atoms.