To preparation of ultra-clean gasoline fuel, a new amphiphilic nanocomposite (TBA-SiWMn@PVA) has been successfully synthesized by supporting sandwich-type silicotungstate polyoxometalate ((n-C4H9)4N)7H5Si2W18Mn4O68 (TBA-SiWMn) on polyvinylalcohol (PVA) as an efficient catalyst for catalytic oxidative desulphurization (CODS) of gasoline. The synthesized materials were characterized by means of elemental analysis, 113Mn NMR, 29Si NMR, XRD, SEM, FT-IR and UV-vis techniques. The catalytic activity of TBA-SiWMn@PVA nanocomposite was tested on real gasoline in the presence of CH3COOH/H2O2 as an oxidant and the results were compared with model sulphur compounds at the same conditions. The TBA-SiWMn@PVA nanocomposite was shown excellent catalytic performance and recoverability for ODS of gasoline with high yield. The effects of the reaction time, reaction temperature, dosage and nature of catalyst were investigated. The reaction mechanism and the kinetic parameters of sulphur compounds oxidation were also discussed. The probable mechanism was proposed via the electrophilic mechanism through the formation of a peroxometalate intermediate complex with phase transfer properties. Results were indicated that the kinetics of sulphur oxidation fitted the pseudo-first-order kinetic model. After 5 oxidation runs, the heterogeneous nanocatalyst was separated and recovered easily.
Keywords: Sandwich-type heteropolyatom; catalyst; gasoline; nanocomposite; polyvinylalcohol.