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

To obtain low-sulfur fuel and reduce SOX emissions, we are developing a MoOX/C hollow sphere catalyst with adjustable oxygen vacancies for oxidative desulfurization (ODS) of fuel. Herein, porous MoOX/C hollow spheres with nanosheet structure were synthesized by pyrolysis of polydopamine-molybdic (PDA-Mo) precursors. The limiting effect of the carbon layer caused MoOX 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 MoOX/C catalysts were employed in oxidative desulfurization (ODS) with H2O2 as an oxidant and displayed excellent performance. The dibenzothiophene (DBT) was eliminated 100% on the optimal catalyst MoOX/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 MoOX 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.