NiMoW/P-Al2O3 Hydrotreating Catalysts: Influence of the Mo/W Ratio on the Hydrodesulfurization and Hydrogenation Activity

Resumo

A series of NiMoW/P-Al₂O₃ catalysts with different Mo/W ratios (sample containing Mo only, Mo/W = 2: 1, Mo/W = 1: 1, Mo/W = 1: 2, and sample containing W only; P₂O₅ content of the support 2.0 wt %) were synthesized. The precursors of the active phase were the heteropoly acids H₃PMo₁₂O₄₀∙nH₂O and H₃PW₁₂O₄₀∙nH₂O, and also nickel citrate. The sulfide phase in the samples was studied by high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy; the catalytic activity of the samples in dibenzothiophene hydrodesulfurization and naphthalene hydrogenation was determined. For the dibenzothiophene hydrogenolysis in the presence of quinoline and naphthalene (content in the model mixture, wt %: dibenzothiophene 0.3, naphthalene 1.5, and quinoline 0.5), k_HDS for different samples is in the range 17.6–42.5 h^–1 at 275°C and 24.6–45.9 h^–1 at 300°C. For the naphthalene hydrogenation, k_HYD varies from 0.79 to 1.89 h^–1 at 275°C and from 0.91 to 3.78 h^–1 at 300°C. The sample based on molybdenum showed the highest activity in hydrogenation and hydrodesulfurization.