Hydrotreating of a Vacuum Gas Oil-Heavy Coker Gas Oil Mixture

Resumo

Changes in the chemical composition of the vacuum gas oil in a mixture with heavy coker gas oil in the presence of industrial and laboratory NiMoW/P₂O₅–Al₂O₃ catalyst were studied. The support used was γ-Al₂O₃, prepared from AlOOH powder TH-60 (Sasol), with the following textural characteristics: S_BET = 205 m²/g, V_pore = 0.682 cm³/g, R_eff = 48 Å. Alumina was modified with P₂O₅ by incipient wetness impregnation with a solution of phosphoric acid (reagent grade), followed by drying and calcination. The catalysts were prepared by incipient wetness impregnation with a combined solution of Mo, W, and Ni compounds. Before the catalytic test, the catalysts were subjected to sulfidation directly in the hydrotreating reactor of a laboratory setup in a stream of H₂S/H₂ = 70/30 vol %/vol % under 0.11 MPa pressure for 2 h at 500°C. The catalytic properties of the catalysts synthesized were examined under the following conditions: temperature of 360 and 390°C, hydrogen pressure of 5.0 MPa, liquid hourly space velocity of 1.0 h^–1, volume ratio of hydrogen to feed of 1000: 1 nL/L, catalyst loading (0.50–0.25 mm fraction) 27 cm³. The reactor temperature was controlled accurately to within 1°C, pressure, to within 0.1 MPa, feed rate, to within 0.2 mL/h, and hydrogen flow, to within 0.2 L/h. During the process the contents of sulfur and polycyclic aromatic hydrocarbons, as well as the hydrocarbon-type content and carbon content of the feed and the hydrogenates, were determined. After the tests the catalysts were studied by differential thermal analysis in combination with thermogravimetry (DTA-TGA).