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

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), N-2 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 center dot OH and center dot O-2 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.

Automated summary

In this work, a new composite material MoOx/MIL-101(Cr) was successfully synthesized for the oxidative desulfurization (ODS) process to remove refractory S-compounds (RSCs) from fuels. The catalyst exhibited remarkable catalytic activity and stability, and the ODS efficiency was found to be related to the formation of Mo5+ species and electron transfer to Mo6+ ions from Lewis acid sites. The study provided insights into the reaction mechanism and confirmed the usefulness of MoOx/MIL-101(Cr) in ODS.