Extractive-Oxidative Desulfurization of Real and Model Gasoline Using (gly)_3HSiW_(12)O_(40)?CoFe_2O_4 as a Recoverable and Efficient Nanocatalyst

摘要

For manufacturing of clean gasoline with a lower S content (e.g., S ＜10 ppm), glycine-modified polyoxotungstate ((gly)_3H[SiW_(12)O_(40)]) was immobilized on cobalt ferrite (CoFe_2O_4) nanoceramics via the sol-gel method and employed as an efficient recyclable nanocatalyst in an extractive-oxidative desulfurization (EODS) system. The synthesized (gly)_3H-[SiW_(12)O_(40)]?CoFe_2O_4 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[SiW_(12)O_(40)]?CoFe_2O_4, nanocatalyst, 60 min reaction time, 35 ℃ reaction temperature, 3 mL of AcOH/ H_2O_2 (V/V ratio of 1∶2) as an oxidant system, and 10 mL of CH_3CN 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[SiW_(12)O_(40)]?CoFe_2O_4 nanocatalyst can reach 9896 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[SiW_(12)O_(40)]?CoFe_2O_4 nanocatalyst after the EODS process.