Oxidation of refractory sulfur compounds with molecular oxygen over a Ce–Mo–O catalyst

Abstract

A Ce–Mo–O catalyst prepared by a simple sol–gel method was proved to be highly active for aerobic oxidative desulfurization. Almost complete conversions of dibenzothiophene and 4,6-dimethyldibenzothiophene were achieved without any additional sacrificial agent at 100 °C and atmospheric pressure, and the conversion of benzothiophene could reach 97%. Reusability of the catalyst was also conducted, and >99% conversions could be achieved in three consecutive runs. As supported by carefully-designed control experiments, oxygen was activated by Ce species in the catalyst first, forming some reactive oxygen species, which oxidized DBT into DBTO₂ with the assistance of Mo species. Furthermore, selective quenching experiments indicated the generation of superoxide species during the reaction.