Effect of lanthanum promotion on the structural and catalytic properties of nickel-molybdenum/alumina catalysts Original Research Article

Effects of lanthanum (La) modification on the surface properties and hydrodesulfurization (HDS) activity of NiMo/Al2O3 catalysts were studied. In the La-modified catalysts, La inhibited the lateral growth of MoS2 layers to form stacked MoS2 layers. The La-modified catalysts slightly enhanced the HDS of 4,6-dimethyldibenzothiophene (4,6-DMDBT) via the hydrogenation (HYD) pathway. The La loading influences the surface concentration of active components, and causes a decrease in surface Ni concentration of the sulfided catalysts. A low La loading (0.7 wt.%) increased the HDS reaction rate constant of the NiMoLa/Al2O3 catalysts by more than 80%, whereas a further increase in the La loading decreased the HDS activity, due to a decrease in the surface Ni concentration.