Effect of alumina and silica-alumina supported NiMo catalysts on the properties of asphaltenes during hydroprocessing of heavy petroleum

(Figure Presented) Asphaltenes were precipitated from a heavy residue and from its hydrotreated products at constant pressure, liquid-hourly space-velocity and hydrogen-to-oil ratio (100 kg/cm², 0.25 h^-1, and 5000 ft³/bbl, respectively). The effect of reaction temperature was studied in the range of 380-410°C. The experiments were carried out in a two fixed-bed reactor unit. The first test used a NiMo/γ-Al₂O₃ catalyst and the second test a NiMo/SiO₂-Al₂O₃ catalyst. It was observed that the molecules of asphaltenes formed after reaction from the NiMo/SiO₂-Al₂O₃ catalyst are smaller in size and less concentrated in metals than those originated from NiMo/γ-Al₂O₃ catalyst, which are more concentrated in nitrogen and the asphaltenes structure is more aromatic. The NiMo/SiO₂-Al₂O₃ catalyst enhances metal removal in liquid products.