Correlation between structural evolution and oxidative desulfurization activity for magnetically-recoverable -Fe₂O₃@SiO₂ core-shell-Supported WO_x nanostructure

In this work, the effect of calcination temperature on the preparation of WOx catalysts supported on gamma-Fe2O3@ SiO2 core-shell nanostructure is reported. Powder XRD and Raman results evidenced that during calcination between 400 and 600 degrees C, the SiO2 shell hinders the phase transition of the formed gamma-Fe2O3 to alpha-Fe2O3, thus maintaining the superparamagnetic characteristics of the core. According to TEM images, a sintering process of SiO2 shell occurs at high temperature, leading to the reduction of the surface area. Because the enhanced dis-persion of dioxo (O=)(2)WO2 species, the gamma-Fe2O3@SiO2 catalyst calcined at 500 degrees C presented impressive performance in the catalytic oxidation of dibenzothiophene.