Abstract
A series of Ni-Mo-P/Al2O3 catalysts with phosphorus added by different methods were prepared. The hydrodesulfurization of 4,6-dimethyldibenzothiophene (4,6-DMDBT) was carried out using the catalysts. The catalysts were also characterized using magic angle spinning nuclear magnetic resonance (MAS NMR).
The hydrodesulfurization activities of phosphorized catalysts were changed from that of NiMo/Al2O3 catalyst. Furthermore, the method for phosphorus addition affected their hydrodesulfurization activities. However, the activation energy and product selectivity for the hydrodesulfurization of 4,6-DMDBT were almost the same for all catalysts. It was indicated that the phosphorus content and the addition method did not change the mechanism of hydrodesulfurization of 4,6-DMDBT.
MAS NMR showed that the phosphorus addition method affected the dispersion of phosphorus on alumina. Catalyst with higher dispersion of phosphorus on alumina showed higher activity for hydrodesulfurization. Phosphorus addition may affect the structure of the molybdenum cluster and the degree of sulfidation of active metal.
