Green and efficient oxidative desulfurization of refractory S-compounds from liquid fuels catalyzed by chromium-based MIL-101 stabilized MoOx catalyst

Abstract

In this work, MoOx/MIL-101(Cr) a new composite material, involving the collaboration of MoOx and MIL-101(Cr) to remove the refractory S-compounds (RSCs) from fuels via oxidative desulfurization (ODS) process were successfully synthesized. The prepared catalyst was characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX), powder X-ray diffraction (P-XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), fourier transform infrared spectroscopy (FT-IR), N2 sorption measurement (BET) and X-ray photoelectron spectroscopy (XPS). The prepared MoOx/MIL-101(Cr) was applied for the ODS of model fuel oil and showed the remarkably catalytic activity for the removal of RSCs from model fuel oil via oxidation. In addition, the effect of Mo-loading amount, H2O2/sulfur (O/S) molar ratio, and reaction temperature on the ODS reactivity were investigated. To explore the specific reaction mechanism of ODS over the MoOx/MIL-101(Cr), the effect of radical scavengers on ODS activity was examined. The radical scavengers experiments showed that the present oxidation reaction occurred through a radical mechanism involving the formation of •OH and •O2͞ species. In addition, it was found that the ODS efficiency is majorly related to the Mo5+ species forming with electron transfer to Mo6+ ion from Lewis acid sites of MIL-101(Cr). Furthermore, the MoOx/MIL-101(Cr) catalyst possesses recycling performance and remarkable stability, and even after five recycles, the removal of DBT was >94.8%. Hence, it could be confirmed that MoOx/MIL-101(Cr) is very useful in the ODS to remove RSCs from fuels in the presence of H2O2.