Preparation of porous hollow spherical MoOX/C catalyst for efficient extraction and oxidative desulfurization.

• Hollow spherical PDA-Mo precursors assembled by polymerization of dopamine hydrochloride with Mo 7 O 24 6-. • In-situ pyrolysis method makes the MoO X active sites highly dispersed. • Oxidation of catalyst enlarge meso-/micro-pores, specific surface area and oxygen vacancies. • MoO X /C catalyst exhibits high ODS performance under mild condition. To obtain low-sulfur fuel and reduce SO X emissions, we are developing a MoO X /C hollow sphere catalyst with adjustable oxygen vacancies for oxidative desulfurization (ODS) of fuel. Herein, porous MoO X /C hollow spheres with nanosheet structure were synthesized by pyrolysis of polydopamine-molybdic (PDA-Mo) precursors. The limiting effect of the carbon layer caused MoO X to be uniformly embedded in the carbon support. Then partial oxidization led to forming more meso-/micro-pores and a larger specific surface area (406.4 m2 g−1), and to obtain crystal and abundant oxygen vacancies, thus increasing the content of effective active sites and enhanced the activity of the composite catalyst. Accordingly, the MoO X /C catalysts were employed in oxidative desulfurization (ODS) with H 2 O 2 as an oxidant and displayed excellent performance. The dibenzothiophene (DBT) was eliminated 100% on the optimal catalyst MoO X /C-750–4 within 15 min at 60 ℃ and had a high turnover frequency (22.6 h−1). Furthermore, in-situ formation of C encompassing MoO X could reduce active site leaching and maintain good reaction stability. After eight recycles, the removal rate of DBT was still 98.6%. This study provides a universal in-situ pyrolysis strategy for constructing supported metal oxides and designing high-capacity ODS catalysts. [ABSTRACT FROM AUTHOR]