▎ 摘　　要

In order to produce ultra-low sulfur fuel, a sandwich-type polyoxometalate (K10[Co4(H2O)2(PW9O34)2]10- (Co4POM) was covalently immobilized on amino-modified magnetic graphene oxide, and employed as a novel heterogeneous catalyst in an extractive- catalytic oxidative desulfurization system (ECODS). The (Co4POM@APTES-(Fe3O4/GO)) nanocomposites with various Co4-POM content were prepared. The obtained samples were characterized by XRD, FT-IR, SEM, EDX, N2 adsorption, and VSM techniques. Meanwhile, the effects of Co4POM load percentage, reaction temperature, catalyst dosage, and H2O2/DBT molar ratio on desulfurization efficiency of the prepared catalyst were investigated. The highest catalytic activity was observed for the sample with 30 wt% Co4-POM content. Dibenzothiophene (DBT) could be completely removed within at 50 degrees C using 4 g catalyst L-1 fuel, and H2O2/DBT molar ratio of 4. In addition, BT and 4,6-DMDBT could be completely removed under the optimized conditions, which suggested a promising prospect of the catalyst for industrial applications. The nanocomposite could be easily separated and reused by utilizing an external magnetic field without any substantial decline in its catalytic activity even after five runs. The kinetic data were fitted to a pseudo-first-order model. Finally, a reaction mechanism for the catalytic oxidation of DBT in the presence of Co4-POM@APTES(Fe3O4/GO) was proposed.