Light straight-run gas oil hydrotreatment over sulfided CoMoP/Al2O3-USY zeolite catalysts

Al2O3 supports were modified by integrating USY zeolites (13.6 wt.%) of various nominal SiO2/Al2O3 molar ratios (30-80). The obtained hybrid solids calcined at 500 °C were impregnated at incipient wetness with a Co-Mo-P solution. After sulfiding with CS2-spiked naphtha (at 230 °C, 5.5 MPa and LHSV=3 h−1) the corresponding catalysts were tested in light straight-run gas oil hydrotreatment at industrially relevant operating conditions. The catalyst containing zeolite of the highest SiO2/Al2O3 molar ratio (80) showed very high hydrodesulfurization activity. Operating at 360 °C, 5.5 MPa and LHSV=2.5 h−1, ultra-low sulfur diesel (∼50 ppm S) could be obtained over that material, from a feedstock of 10,400 ppm S. Medium-strong acidity could be playing an important role on this behaviour by promoting isomerization of sterically hindered organo-sulfur compounds to more favorable configurations. Moreover, hydrodearomatization and hydrodenitrogenation were also enhanced by addition of that high-silica zeolite.