Performances, kinetics and mechanisms of catalytic oxidative desulfurization from oils

Ultra-deep desulfurization technologies are critical for cleaner oils and consequent better air quality. Earlier efforts in this field focused on specific catalysts and their catalytic efficiencies, while current interest has shifted to the differences between homogenous and heterogeneous catalysis systems applied in catalytic oxidation desulfurization (ODS) as well as their advantages and disadvantages. In this review, catalysts using various supports were described and their catalytic activities in total oxidation of sulfur compounds were evaluated and commented meanwhile, taking hydroperoxide as oxidant. Then, the effects of reaction parameters on catalyst activities and the kinetics and mechanisms that were used for ODS from oils were reviewed. Under the same conditions, heterogeneous catalysts performed better than homogeneous catalysts. Leaching of active components, existence of N-containing compounds and excessive reaction temperature would deactivate catalysts in ODS. Besides, power-law kinetics equations, Langmuir-Hinshelwood mechanism, and nucleophilic attack reaction mechanism will provide in-depth analysis of desulfurization process and catalysts deactivation. Future research needs on ODS are proposed including the development of novel carrier materials, the optimization of acid sites distribution and the better understanding of deep reaction mechanisms.