Ultrasound-assisted hydrothermal synthesis of v₂o₅/zr-sba-15 catalysts for production of ultralow sulfur fuel

This work reports the results of the ultrasound-assisted hydrothermal synthesis of two sets of V₂O₅ dispersed on SBA-15 and Zr doped SBA-15 catalysts used for the oxidation of dibenzothio-phene (DBT) in a model diesel via the combination of oxidation, catalysis, and extraction technical route. These catalysts contained Lewis acidity as major and Brønsted acidity as minor. The amount of acidity varied with the content of vanadia and zirconium doping. It was found that DBT conversion is very sensitive to the Lewis acidity. DBT conversion increased by increasing the vanadium content and correlated well with the amount of surface Lewis acidity. Under the optimal experimental condition (Reaction temperature: 60^◦C, reaction time 40 min, catalyst concentration: 1 g/L oil; H₂O₂/DBT mole ratio = 10), the 30% V₂O₅/SBA-15 and 30% V₂O₅/Zr-SBA-15 catalysts could convert more than 99% of DBT. Two reaction pathways of DBT oxidation involving vanadia surface structure, Lewis acidity, and peroxometallic complexes were proposed. When the vanadia loading V₂O₅ ≤ 10 wt%, the oxidative desulfurization (ODS) went through the Pathway I; in the catalysts with moderate vanadia content (V₂O₅ = 20–30 wt%), ODS proceeded via the Pathways II or/and the Pathway I.