Oxidative desulfurization of model fuel in the presence of molecular oxygen over polyoxometalate based catalysts supported on carbon nanotubes

With the emergence of environmental problems such as acid rain and haze, the study on fuel desulfurization has become an important subject of environmental protection. Oxidative desulfurization (ODS) becomes the promising method due to its mild reaction condition, low cost and high efficiency. In this work, two series of catalysts supported by carbon nanotubes (CNTs) are prepared by two different procedures: a) the polyoxometalate (POM) is impregnated into the channel of CNTs by impregnation method, b) the modified CNTs is wrapped by polyoxometalate through ion exchange method. The novel catalysts are investigated by FT-IR, XRD, XPS, SEM and N-2 adsorption-desorption isotherms. The desulfurization performance of all catalysts is carried out under a certain condition, and the catalysts have positive effects on dibenzothiophene (DBT) conversion. The effect of factors on desulfurization is evaluated, and the favorable conditions are determined. Based on optimal conditions, the DBT conversion reached up 99.4%, and the desulfurization system could be recycled 8 times without noticeable decrease in activity. In addition, the impact of the critical parameters (temperature, mass of catalyst and oxygen quantity) was investigated using Box-Behnken experimental design. The optimum simulation condition is consistent with the experimental investigation, which further proves the accuracy of the experimental conclusion.