Hydrogenation of aromatic hydrocarbons in the presence of dibenzothiophene over platinum-palladium catalysts based on Al-SBA-15 aluminosilicates

Abstract

The hydrogenation of a 2-methylnaphthalene solution in n-heptane in the presence of dibenzothiophene (400 ppm in terms of sulfur) over Pt-Pd catalysts containing Al-SBA-15 mesoporous aluminosilicates has been studied. Supports for the catalysts contained 35 wt % Al-SBA-15 and 65 wt % γ-Al₂O₃. The Pt and Pd contents of the catalysts was 0.25 and 1.0 wt %, respectively. Experiments with the model feedstock were conducted in an autoclave at 240–260°C, an initial hydrogen pressure of 30 atm, and a substrate/metal weight ratio of 30. It has been found that a catalyst based on Al-SBA-15 with Si/Al = 5 exhibits the highest activity under poisoning with 400 ppm sulfur. Thus, the conversion of 2-methylnaphthalene at 260°C after 3 h was 85% with the selectivity for methyltetralins of 97%. The dearomatization of a hydrotreated diesel fraction with 45 ppm sulfur at 260°C at a pressure of 30 atm and a space velocity of 2.4 h⁻¹ has made it possible to decrease the total aromatic content, in particular reduce the concentration of polycyclic aromatic compounds to a level of less than 1 wt %.