(Ni)W/ZrO2 hydrotreating catalysts prepared in molten salts Original Research Article

(Ni)W/ZrO2 oxide catalysts have been prepared using reactions in molten Na(K)NO3 fluxes at different temperatures ranging from 350 to 500 °C. The solids were characterized using X-ray diffraction (XRD), textural measurements and X-ray photoelectron spectroscopy (XPS). Highly dispersed zirconia with tungstate species grafted on its surface was formed at 450–500 °C. At 350–400 °C tungsten oxide or crystalline intermediate polytungstates of K and Na were observed in the products. Specific surface areas of the solids were high, up to 250 m2/g, due to stabilizing effect of tungstate species. After sulfidation, the catalysts were studied by XPS in situ, and tested in the model reactions of hydrodesulfurisation (HDS) and hydrogenation (HYD). XPS study reveal incomplete sulfidation of tungsten even at 500 °C, suggesting some persistent Zr–O–W bonds. Compared with conventional impregnation NiMo/Al2O3 systems, the (Ni)W/ZrO2 solids showed increased hydrogenating activity.