High-Entropy metal oxide with enhanced catalytic performance and magnetic recovery for Ultra-Deep desulfurization of fuel oils

• High-entropy metal oxide (HEO-M−900) enables efficient ACODS with molecular O 2 . • Magnetic separability of HEO-M−900 allows easy recovery after ACODS. • Defect sites in HEO-M−900 enhance sulfur compound adsorption and oxidation . • Superoxide radicals generated by HEO-M−900 drive ultra-deep desulfurization. • HEO-M−900 maintains high catalytic performance and reusability across cycles. In this work, we reported the synthesis of a high-entropy metal oxide catalyst, HEO-M−900, with a focus on its exceptional performance in the catalytic adsorptive coupled with oxidative desulfurization (ACODS) of fuel oils. The HEO-M−900 catalyst, composed of Mo, Ni, Co, Fe, V, and O, exhibits an optimized high-entropy structure as well as numerous defects, as confirmed by a series of characterizations. The electron transfer between metals in the HEO-M−900 enhances the adsorption of aromatic sulfides and the activation of O 2 , resulting in superior catalytic efficiency. Mo becomes more electron-rich, effectively activating O 2 to generate reactive superoxide radicals (·O 2 – ), while Ni, Co, and V, which lose electrons, improve sulfide adsorption. Notably, the incorporation of magnetic elements (Fe, Co, and Ni) in HEO-M−900 enables efficient magnetic separation and recovery of the catalyst, as demonstrated by vibrating sample magnetometer (VSM) measurements. The HEO-M−900 catalyst achieved 100% desulfurization in model oils within 8 h at 120 °C, with resistance to olefin and aromatic interference. Recyclability tests, which can be realized by magnetic separation, showed that HEO-M−900 retained over 96.4% activity after 14 cycles, maintaining structural stability despite minor accumulation of DBTO 2 on the surface. The synergistic effect of enhanced adsorption, improved catalytic oxidation, and magnetic recoverability makes HEO-M−900 a promising candidate for practical ACODS applications.