PERFORMANCE, CHARACTERIZATION, AND SURFACE-ACIDITY OF ZIRCONIUM MODIFIED HYDROPROCESSING CATALYSTS

Gas-oil hydrodesulfurization activity of Ni-Mo/Al2O3 catalysts was sig nificantly improved when prepared with zirconium alkoxide, but lowered when prepared with Zr nitrate. IR of CO adsorption on reduced catalys ts, and LRS and XPS of calcined catalysts show that the addition or zi rconium does not effect the metal oxide structure. IR of pyridine adso rption and Al-27 NMR both show greatly enhanced Lewis and Bronsted aci dities of the Zr alkoxide modified materials as compared to unmodified samples. These results point to the strong influence of surface acidi ty on activity in hydroprocessing catalysts.