Silicotungstate@ZIF-67 as an effective catalyst for an extraction and oxidative desulfurization system

Through a simple room-temperature process, different amounts of Keggin-type quaternary ammonium silicotungstate were successfully encapsulated into the metal–organic framework (MOF) material ZIF-67. The catalysts were characterized using Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and BET analysis. An extraction and catalytic oxidation desulfurization system was studied using H₂O₂ as an oxidant and a deep eutectic solvent (DES) as an extractant. Using the 43.06%-SiW₁₂@ZIF-67 composite under optimal reaction conditions, DBT present in a model oil could be deeply and effectively removed. The catalyst was reused 6 times, and the desulfurization rate still exceeded 90%. Finally, a possible desulfurization mechanism is proposed.