Preparation of magnetic urchin-like NiCo2O4 powders by hydrothermal synthesis for catalytic oxidative desulfurization

Abstract

In this manuscript, magnetic NiCo₂O₄ powder was prepared by hydrothermal synthesis and utilized as a catalyst to remove dibenzothiophene (DBT) from n-octane. The results showed that the average particle size, Langmuir surface area, and average pore diameter of synthetic NiCo₂O₄ powders were 15 nm, 998.7 m² g⁻¹, and 19.6 nm, respectively. The magnetic urchin-like NiCo₂O₄ powder formed by linear directional agglomeration of rectangular NiCo₂O₄ nano-flakes followed by agglomeration of NiCo₂O₄ nano-wires, and subsequently urchin-like agglomeration of NiCo₂O₄ bundles. The NiCo₂O₄ powder exhibited excellent magnetic separation ability, recycling stability, and catalytic activity. The NiCo₂O₄ powder activated peroxymonosulfate (PMS) to produce a highly reactive oxygen species for oxidizing DBT to DBT-sulfoxide. The sulfur removal was ∼98% under the following optimum conditions: 6 mL of model oil (600 ppm), PMS with oxygen to the sulfur ratio of 3 : 1, 0.5 g of NiCo₂O₄ powder, 40 °C, and 20 min. Interestingly, the NiCo₂O₄ catalyst maintained high activity after being reused five times.