Structure Investigation and Dibenzothiophene Hydrodesulfurization Properties of Fe-Substituted Ni–Si Intermetallics

Abstract

Development of highly active and sulfur-tolerant catalysts for deep hydrodesulfurization (HDS) is of great importance in petroleum refining. Here, the discovery of Fe-substituted Ni–Si intermetallic catalysts (Ni1–xFexSi2) that efficiently removes dibenzothiophene (DBT) by HDS is reported. The structure of the catalyst was identified through X-ray diffraction, Mossbauer spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results showed that Fe atoms substituted Ni atoms in Ni1–xFexSi2 catalysts, which preferentially bond with Ni to form alloy and combine with Si to form silicide. The DBT activity for the Ni1–xFexSi2 has the following order: Ni0.75Fe0.25Si2 > NiSi2 > Ni0.50Fe0.50Si2 ≈ Ni0.25Fe0.75Si2 ≈ Fe–Si. The positive synergistic effect on HDS activity can be correlated to that the formation of Ni–Fe and Fe–Si bonds makes the metal site to have high d-electron density, which promotes the hydrogenation activity. Comparison with the fresh and spent catalysts revealed...