Active Phase of a NiSO4 Catalyst Supported on γ-Al2O3 during in Situ Self-Sulfidation for Selective Hydrodesulfurization

Abstract

NiSO4/γ-Al2O3 catalysts with different Ni loadings were prepared by impregnation with an aqueous solution of nickel sulfate. The samples were characterized by X-ray powder diffraction, nitrogen physisorption, X-ray fluorescence, NH3 temperature-programmed desorption, UV Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). XPS showed that the nickel sulfate can be partly in situ self-sulfided to NiSx by H2 at an elevated temperature, especially when H2S is present in the reactor. The catalytic performances of NiSO4/γ-Al2O3 catalysts were evaluated with a mixture of 2-methyl-2-butene, cyclohexane (3:97, volume ratio), and thiophene (0.1%, ratio of total weight) as a model feedstock. The 5-NiSO4/γ-Al2O3 catalyst showed high activity in terms of high thiophene conversion (89%) and a high selectivity factor, 3.2. The kinetic study and Koros–Nowak test were carried out, and it was found that the pre-exponential factor (k0) and apparent activation energy (Ea) of thiophene hydrodesulfurization (HDS) we...