An electronic structural study of Ni-Mo-S hydrodesulfurization (HDS) catalysts

Tadao. Shibuya ( tadao-DOT-shibuya-AT-si-DOT-idemitsu-DOT-co-DOT-jp.gif ), H. Koshika, T. Umeki, and K. Inamura
Idemitsu Kosan Co.,LTD Central Reseach Laboratories, Japan.

It is well known that the HDS activity of alumina-supported MoS2 catalyst is highly enhanced by adding Ni (Co). However, the relationships between the role of these added elements and the detailed structures of the active sites have not been well understood.

We have investigated the electronic structures of Ni-added MoS2 cluster models by using a DFT (Density Function Theory) molecular orbital method (DMol3). Some of MoS2 clusters were organized and determined the electronic structures by changing the number of Mo atoms from 5 to 27, while reserving a C2v (or D3h) symmetry. In the next step, some of Ni atoms were positioned in the place of the Mo atoms of the MoS2 clusters. These Ni modified clusters showed some changes of electronic structures such as electron density distributions and HOMO-LUMO contributions of each atom, which may affect the HDS reaction mechanisms.