Oxidative desulfurization of dibenzothiophene compounds with titania based catalysts

Titanium oxide nanotubes (TiN) and a titanium-substituted mesoporous SBA-15 molecular sieve were synthesized, characterized and tested in oxidative desulfurization (ODS) of dibenzothiophene compounds prevailing in diesel fuel. Two commercial titanias were used as references. The structural and textural properties of the titania based catalysts were characterized by X-ray diffraction (XRD), transmission and scanning electron microscopy (TEM and SEM-EDX), and nitrogen adsorption–desorption measurements. The ODS tests were carried out in three-phase (L–L–S) system but also in a two-phase (L–S) system to evaluate the oxidation taking place in the liquid phase only. The reaction results indicate that the best catalytic performance is achieved with TiN and that for the most active catalysts the removal of sulfur could be limited by the mass transfer between the two liquid phases (solvent extraction and oil).

Graphical abstractDBT-sulfone yields vs. ODS reaction time with several Ti-based catalysts: titanium oxide nanotubes (TiNs), TiN calcined at 300 °C (TiNC), titanium-substituted mesoporous SBA-15 molecular sieve (Ti-SBA-15), and commercial titanias; Hombiteck (TiH) and Degussa (P25).Figure optionsDownload full-size imageDownload high-quality image (159 K)Download as PowerPoint slideResearch highlights► Titanium oxide nanotubes are highly active for the ODS of DBTs. ► Ti-SBA-15 molecular sieve presents high activity and is a promising catalyst for ODS. ► S removal could be limited by the mass transfer between liquid phases in L–S–S system.