Oxidative desulfurization of dibenzothiophene and diesel over [Bmim]3PMo12O40

A hybrid material ([Bmim]3PMo12O40) was synthesized by reacting H3PMo12O40 with the ionic liquid 1-butyl-3-methyl imidazolium bromide. SiO2-supported [Bmim]3PMo12O40 showed a high catalytic activity in the oxidation of dibenzothiophene (DBT) with 29% H2O2 aqueous solution as the oxidant. Maximum activity was observed at a loading of 20 wt.% [Bmim]3PMo12O40 on SiO2, and 100% DBT conversion was achieved at 60 °C, atmospheric pressure, and an oxygen to sulfur (O/S) molar ratio of 3.0 in 100 min. The high performance of [Bmim]3PMo12O40/SiO2 might be attributable to its amphiphilicity, which enhances adsorption of both H2O2 and sulfur-containing compounds. [Bmim]3PMo12O40/SiO2 could be easily separated by centrifugation and reused without deactivation after seven runs. Quinoline and carbazole had slightly positive effects on DBT oxidation, whereas indole had a negative effect. The high performance of [Bmim]3PMo12O40 was verified in the sulfur removal from a real diesel by means of oxidation followed by dimethylformamide extraction.

Graphical abstract[Bmim]3PMo12O40/SiO2, which is amphiphilic, exhibits high catalytic performance in the oxidation of dibenzothiophene and a real diesel. Quinoline and carbazole show slight promoting effects, whereas indole strongly inhibits the oxidation.Figure optionsDownload full-size imageDownload high-quality image (72 K)Download as PowerPoint slideResearch highlights► [Bmim]3PMo12O40/SiO2 is an outstanding catalyst in oxidative desulfurization. ► The aqueous phase adsorbs on catalyst particles, which work like microreactors. ► The aqueous phase and solid catalyst are separated simultaneously from oil phase. ► The dried spent catalyst was reused for seven runs without deactivation. ► Nitrogen compounds may have positive or negative effects.