Effect of NiMo phases on the hydrodesulfurization activities of dibenzothiophene

Abstract

Preparation of highly-active hydrodesulfurization (HDS) catalysts draws increasing attention due to environmental concerns. Now the effects of various NiMo phases on the HDS activities are investigated. Calcinations of a series of PVP-assisted synthesized NiMo oxides led to NiMo precursors with various phases. The NiMo precursors and sulfided catalysts were characterized by XRD, N2 isotherm, FT-IR, SEM, and TPR, and the activities of the NiMo catalysts were obtained in the HDS reactions of dibenzothiophene (DBT). Results revealed that the phases of α-, β-NiMoO4, and ammonium nickel molybdate were detected on the NiMo precursors. A NiMo-0.5 precursor with a H2-type hysteresis loop had very high BET surface area (144m2g−1), which was higher than traditional metal oxides. Phases of MoS2 and Ni3S2 nanoparticles were detected on the sulfided NiMo catalysts. Catalytic results reveal that the sulfided NiMo catalysts deriving from β-NiMoO4 phase were more active than those from the α-NiMoO4 phase. A NiMo-0.1 catalyst had higher HDS activities towards DBT than the other NiMo catalysts, due to the phase of β-NiMoO4 and easy reductions of nickel oxide and molybdate, which might be beneficial for the formation of ‘NiMoS’ active phase. These findings show that for the preparations of highly-active unsupported and supported NiMo catalysts, the β-NiMoO4 phase is preferred, which provides more useful information in the development of HDS catalysts.