Extractive–Oxidative Desulfurization of Real and Model Gasoline Using (gly)3H[SiW12O40]⊂CoFe2O4 as a Recoverable and Efficient Nanocatalyst

For manufacturing of clean gasoline with a lower S content (e.g., S <10 ppm), glycine-modified polyoxotungstate ((gly)3H[SiW12O40]) was immobilized on cobalt ferrite (CoFe2O4) nanoceramics via the sol–gel method and employed as an efficient recyclable nanocatalyst in an extractive–oxidative desulfurization (EODS) system. The synthesized (gly)3H[SiW12O40]⊂CoFe2O4 nanocatalyst was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) techniques. The optimum conditions for the reaction are given as follows: 50 mL of model and real gasoline, 0.10 g of (gly)3H[SiW12O40]⊂CoFe2O4 nanocatalyst, 60 min reaction time, 35 °C reaction temperature, 3 mL of AcOH/H2O2 (V/V ratio of 1:2) as an oxidant system, and 10 mL of CH3CN solvent as an extractant. Based on optimization results under the mentioned conditions and the proposed EODS system, the removal efficiency (%) of the model fuel utilizing the (gly)3H[SiW12O40]⊂CoFe2O4 nanocatalyst can reach 98% with stable reusability up to five times without a noticeable decrease in its catalytic activity. Correspondingly, 0.4986 ppm S content in real gasoline could decline to 0.0145 ppm with a removal yield of 96% under identical conditions. Also, the kinetics of the EODS reactions was found to be pseudo-first order, and the EODS mechanism was put forward through the generation of a peroxometalate intermediate complex with phase transfer properties. The present research shows that liquid fuels can be purified into ultralow-sulfur fuels through highly oxidative desulfurization via the (gly)3H[SiW12O40]⊂CoFe2O4 nanocatalyst after the EODS process.