Oxidative Desulfurization of Lighter Petroleum Fractions Using Supported Heteropoly-Acid Catalysts (A Review)

Desulfurization is a significant problem in fuel refining. Hydrodesulfurization was the subject of extensive research for many years as a commercial and conventional method to remove sulfur compounds. However, the removal of organic sulfur compounds by hydrodesulfurization became more challenging with increasingly stringent environmental policies on fuel. As a result, non-hydrodesulfurization methods have advanced quickly in the last several years. Oxidative desulfurization (ODS), with its mild reaction conditions and high efficiency, performs best of all new desulfurization technologies. ODS is one of several synthetically selective transformations of organic substances that use heteropoly acids (HPAs). HPAs, which have a distinct ionic structure and high proton mobility, have been extensively studied for their great potential for catalysis. Nevertheless, HPAs have drawbacks, including their limited specific surface area and high solubility in polar solvents. Numerous attempts have been made to combine HPAs with other materials to overcome these limitations. Supported HPAs, polyoxometalate-based ionic liquids, and phase-transfer HPAs are the primary HPA derivatives used in ODS as catalysts. Following modification, HPAs’ catalytic activity and reusability are significantly enhanced.