Effect of Calcination Temperature of Unsupported NiMo Catalysts on the Hydrodesulfurization of Dibenzothiophene

The effects of NiMo catalyst calcination temperature (250, 350, 450, 550, and 650 °C) on catalytic hydrodesulfurization of dibenzothiophene (DBT) were studied. The physiochemical properties of the unsupported NiMo catalysts were characterized by various techniques, including N 2 adsorption–desorption, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). XRD and FT-IR results showed that increasing the calcination temperature brought about a phase change of the NiMo catalyst precursors from ammonium nickel molybdate to nickel molybdate. The agglomeration of precursor particles and MoS 2 nanoclusters changed with various calcination temperatures as revealed by SEM and HRTEM, respectively. DBT catalytic results showed that the NiMo catalyst calcined at 350 °C exhibited higher activity than other NiMo catalysts, and the selectivity of bicyclohexane was much preferred at a reaction temperature of 320 °C over NiMo catalysts endowed with the phase of ammonium nickel molybdate. The high hydrogenation ability might be due to the efficient formation of the “Ni-Mo-S” phase and will be attractive for industrial applications.