Synthesis of a Ti-SBA-15-nimo hydrodesulfurization catalyst: The effect of the hydrothermal synthesis temperature of nimo and molybdenum loading on the catalytic activity

We report herein the investigation of the catalytic activity on the hydrothermal synthesis temperature (HTsynT; 60-120 °C) and molybdenum loading (5-13 wt %) of NiMo catalyst supported over titanium-modified mesoporous silica (Ti- SBA-15) for the simultaneous hydrodesulfurization (HDS) of dibenzothiophene (DBT) and 4-methyldibenzothiophene (4- MDBT) in dodecane. It was found that the dispersion of an NiMo active phase in a one-pot synthesis is size-dependent and mostly controlled by the HTsynT for an efficient HDS catalytic performance. The as-developed catalysts were characterized by N2 physiosorption, X-ray diffraction (XRD), temperature-programmed techniques, and scanning electron microscopy. XRD analysis revealed that MoO3 particles agglomerate to form a high crystalline phase, as a function of the hydrothermal temperature and molybdenum loading, which, in turn, affects the textural properties, number of active sites, and reduction temperature. The catalytic performance for the simultaneous HDS of DBT and 4-MDBT was evaluated at 350 °C and 5 MPa in a batch autoclave reactor. The results show that a HTsynT of the Ti-SBA-15-NiMo catalyst above 100 °C leads to a marked decrease in the catalytic performance. The effect of the molybdenum loading on the catalytic performance was also influenced by the HTsynT. A hydrothermal temperature of 80 °C and a molybdenum loading of 8 wt % resulted in improved overall HDS activity. However, HDS by a desirable direct desulfurization route was favored over a catalyst with 13 wt % molybdenum loading.