Generation of isolated Ti4+ sites via one-pot synthesis of mesoporous Ti-SBA-15 catalysts for high-performance oxidative desulfurization of dibenzothiophene

Abstract

Ti-incorporated SBA-15 catalysts were synthesized via a one-pot hydrothermal method and tested in the liquid-phase oxidative desulfurization (ODS) process at 80 °C and atmospheric pressure for low-sulfur fuel production. These catalysts exhibited superior ODS performance compared to conventional impregnation-based catalysts. Characterization confirmed the successful incorporation of titanium ions into the SBA-15 framework, forming Si–O–Ti bonds with tetrahedrally coordinated Ti⁴⁺ species. Two types of Ti⁴⁺ sites—crystalline and isolated—were identified, with the isolated sites contributing more significantly to catalytic activity. The high accessibility of dibenzothiophene (DBT) to isolated Ti⁴⁺ sites, along with the minimal presence of crystalline TiO₂ phases, were key factors in the enhanced performance. Quantitative analysis showed that isolated Ti⁴⁺ sites exhibited a turnover frequency (TOF) approximately 20 times higher than that of crystalline Ti⁴⁺ sites, confirming their role as the primary active sites in the ODS reaction.