A new multi–metallic bulk catalyst with high hydrodesulfurization activity of 4,6–DMDBT prepared using layered hydroxide salts as structural templates

Abstract

Layered multi–metallic bulk catalysts NixZnyMoW with different Ni/Zn molar ratios were prepared based on the NiZn–layered hydroxide precursor by co–precipitation method and well characterized by various technologies including XRD, SEM, HRTEM and Raman spectroscopy. HRTEM images illustrated that both the slab sizes and stacking layers of sulfided catalysts were changed with different Zn contents. These catalysts were tested for hydrodesulfurization (HDS) of 4,6–dimethyldibenzothiophene (4,6–DMDBT) from model diesel. Hydrodesulfurization (HDS) reaction of 4,6–dimethyldibenzothiophene showed that all the catalysts NixZnyMoW with layered structure exhibited high HDS activity and the sulfur content in the model diesel can be reduced from 517ppm to less than 10ppm under mild reaction conditions of 3.0MPa of H2 pressure, 300°C, a LHSV of 9h−1, and H2/oil ratio of 800Ncm3/cm3. The catalysts NixZnyMoW have shown much higher specific HDS activity than that of the commercial catalyst CoNiMoW/Al2O3. However, ZnMoW without Ni has shown relatively low activity. The higher HDS activity of NixZnyMoW could be ascribed to high contents of active metals and the layered structure. Meanwhile, the synergism between Ni/Zn and Mo/W plays an important role in achieving the excellent HDS performance of catalysts NixZnyMoW.