Removal of dibenzothiophene by extraction and catalytic oxidation using long- and short-channel SBA-15 containing Zr and Mo species

Abstract

Two different SBA-15 silicas with long and short channels, containing zirconium species, were prepared and used as supports for molybdenum additives. The resulting materials were characterized and tested as catalysts for extractive catalytic oxidative desulfurization (ECODS) of dibenzothiophene (DBT) using acetonitrile as a solvent and H₂O₂ as an oxidant. The synthesis procedure for the zirconium-containing silicas influenced both the zirconium loading and its distribution, i.e., whether it was incorporated into the framework or present in extra-framework positions. Additionally, the choice of support for molybdenum inclusion affected the amount of modifier loaded and its resistance to leaching, which collectively impacted the acidic and basic properties of the synthesized catalysts. The textural and surface properties of the materials were evaluated using low-temperature nitrogen adsorption/desorption, XRD, SEM-EDS, FT-IR-ATR, XPS, and UV-vis. The acidity and basicity of the samples were evaluated using FT-IR spectroscopy with pyridine adsorption/desorption and test reactions including 2-propanol dehydration/dehydrogenation and 2,5-hexanedione cyclization/dehydration. The catalytic activity was measured in ECODS. The Mo/ZrSBA-15-S catalyst demonstrated the best performance in DBT removal from the oil phase, achieving approximately 92% conversion of DBT within 120 minutes at 60 °C. This superior activity was attributed to the material's high acidity strength.