Sulphide catalysts on silica as a support: VI. On the structures of the active phase and active centers of hydrodesulphurization catalysts

Abstract

Based on the experimental data of the study of highly dispersed sulphided (Ni-W)/SiO 2 and (Ni-Mo)/SiO 2 catalysts prepared from organometallic precursors, the structures of the active phase and active centers for C S bond hydrogenolysis are discussed. The active phase of hydrodesulphurization catalysts represents layered sulphide structures with the same M S and M M (M W or Mo) distances as in bulk disulphides. A single MS 2 sheet is a sufficient structural element for the formation of active centers. It was suggested that the active centers include Ni atoms, on which thiophene adsorption occurs, and W(Mo) atoms of the side planes of the MS 2 sheet. Sulphur atoms bound with one Ni atom are involved in the catalytic cycle.