Hydrotreating of Vacuum Gas Oil on NiW/Al2O3 Catalysts Prepared with the Use of Chelating Agents

Resumo

Alumina-based NiW catalysts have been prepared from 12-phosphotungstic heteropoly acid (PW₁₂HPA), ammonium metatungstate (NH₄)₆H₂[W₁₂O₄₀], and nickel hydroxide carbonate or nickel nitrate using citric acid (CA) or ethylenediaminetetraacetic acid (EDTA) as a chelating agent. The obtained samples have been studied by N₂ adsorption, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy techniques. The catalysts obtained using the PW₁₂HPA and CA have been characterized by the greatest dispersion of active-phase particles, and the use of EDTA has provided the maximum proportion of NiWS. The hydrodesulfurizing activity of catalysts in the hydrotreating of vacuum gas oil has been found to decrease in the following order: Ni-CAPW/Al₂O₃ > Ni-CAW/Al₂O₃ > Ni-EDTA-W/Al₂O₃ > Ni-W/Al₂O₃, which in general correlates with the particle size of the active phase and the concentration of promoted active sites.