Preparation of WO₃/g-C₃N₄ heterojunction catalyst and its oxidative desulfurization performance

Graphite phase carbon nitride (g-C₃N₄) and metal oxide tungsten trioxide (WO₃) heterojunction nanocomposites WO₃/g-C₃N₄ were prepared by roasting from urea and ammonium tungstate. The physical and chemical properties of the catalysts were investigated by means of XRD, UV-vis, SEM, PL and XPS. The characterization indicated that WO₃ and g-C₃N₄ interacted well in the catalysts, and electron transfer occurred between them, which ensured high oxidative desulfurization activity of WO₃/g-C₃N₄. Supported catalyst WO₃/g-C₃N₄ was prepared using WO₃ as the support. Isopropyl peroxide was used as the oxidant to investigate the catalyst performance in oxidative desulfurization of the simulated oil. Under the reaction conditions of 80℃ and the content ratio of O/S at 3, a 72.79% of dibenzothiophene (DBT) conversion could be achieved after 180 min. It was fund that the superoxide free radicals (·O₂^-), electron (e^-) and hydroxyl free radicals (·OH) promoted the reaction rate through free radical capture experiment and the reaction mechanism was proposed.