Elucidation of sulfidation state and hydrodesulfurization mechanism on Mo/TiO2 catalyst using 35S radioisotope tracer methods

Abstract In hydrodesulfurization (HDS) of dibenzothiophene (DBT) the activities on the Mo/TiO 2 catalysts with various Mo contents were estimated under the typical HDS reaction conditions. The results show that the activities of the catalysts increased linearly with Mo content up to 6 wt.% MoO 3 , which means that the monolayer dispersion of MoO 3 on TiO 2 support is maintained up to 6 wt.% MoO 3 . The sulfidation states of MoO 3 /TiO 2 catalysts were investigated using a 35 S radioisotope pulse tracer method. The results showed that the sulfidation of TiO 2 support would also occur. Moreover, the sulfur mobility on the sulfided 6% MoO 3 /TiO 2 catalyst under the reaction conditions was elucidated by a 35 S radioisotope tracer method using 35 S -labeled DBT. The results suggested that, compared to Mo/Al 2 O 3 catalyst, Mo/TiO 2 catalyst showed a little higher amount of labile sulfur ( S 0 ) and about two times higher release rate constant of H 2 S ( k RE ), which indicated that higher mobility of sulfur was obtained on sulfided Mo/TiO 2 catalyst.