Key Factors Affecting the Development of Oxidative Desulfurization of Liquid Fuels: A Critical Review

Complete and effective sulfur removal from liquid fuels is essential to meet the sulfur standard requirements. The oxidative desulfurization (ODS) process has been extensively used for the desulfurization of liquid fuels. In the current study, a comprehensive survey was conducted on the most important factors of ODS, including the types of catalysts, oxidizing agents, extraction solvents, liquid fuels, and process operating conditions. Various types of catalysts, nanocatalysts, magnetic catalysts, photocatalysts, electrocatalysts, biocatalysts, and emulsion catalytic systems have been studied in the ODS process. According to the obtained results, desulfurization catalysts were categorized into 11 groups, including metal oxides, metal complexes, metal free, titanosilicates, ionic liquids, polyoxometalates, metal–organic frameworks, porous aromatic frameworks, covalent organic frameworks, enzymes, and Fenton and Fenton-like catalysts. The advantages and drawbacks of the ODS catalysts were reviewed. The results indicate that the development of experimental design, modeling, and simulation in the ODS process helps to identify the most important variables, facilitate future research, and achieve maximum sulfur removal. Using technologies assisted with ODS such as ultrasound, cold plasma, microwave radiation, hydrodynamic cavitation, photo/light, electrochemistry, magnetic field, and biotechnology can improve sulfur removal and reduce reaction time.