Pt-containing high-entropy oxide confined in SBA-15 for efficient extractive–oxidative desulfurization

Abstract

Combustion of diesel and other fuel oils releases sulfur oxides (SO_x) from their inherent organosulfur compounds, causing exhaust catalyst deactivation and severe environmental pollution. Given the limitations of conventional hydrodesulfurization (HDS) in removing refractory sulfur species under mild conditions, developing efficient oxidative desulfurization (ODS) strategies has become increasingly important. To address this challenge, a supported high-entropy metal oxide catalyst, HEO(Pt)@SBA-15, was synthesized using mesoporous SBA-15 as the support and Pt in high-entropy oxide (HEO) as the primary active component. Detailed characterization demonstrated that the high-entropy oxide was successfully confined within the mesoporous framework. The subsequent dispersion of the HEO(Pt)@SBA-15 catalyst in the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF₄) yielded a heterogeneous ionic-liquid catalyst designated HEO(Pt)@SBA-15-B. This hybrid catalyst integrates strong extractive capability with the robust oxidation properties of the high-entropy oxide. In extractive-coupled catalytic oxidative desulfurization (ECODS) of diesel, HEO(Pt)@SBA-15-B exhibited remarkable efficiency arising from the synergistic interplay between ionic-liquid extraction and catalytic oxidation. Complete removal of dibenzothiophene was achieved within 5 h under optimized conditions, and the catalyst retained 94.2% DBT conversion after five consecutive cycles, demonstrating excellent stability and reusability.