Catalyst Support Strategies: Encapsulation of Polyoxometalate Catalysts in Magnetic Particles in Oxidative Desulphurization

High sulphur levels in liquid fuels increase sulphur oxide emissions upon combustion, exacerbating environmental and health risks. This makes desulphurization critical in fuel refining processes to reduce sulphur content. Among several methods, oxidative desulphurization (ODS) has become increasingly recognized due to its mild operating conditions and efficiency in the removal of refractory sulphur compounds, such as dibenzothiophene (DBT) and benzothiophene (BT), from fuels. The sulphur conversion efficiency of ODS is influenced by several key parameters: reaction duration, operating temperature, the type and concentration of oxidant, and the nature and dosage of the catalyst. While polyoxometalates (POMs) exhibit excellent catalytic activity for ODS, their application is limited by their homogeneous nature and poor recoverability. To address these challenges, recent advancements have focused on enhancing their performance through heterogeneous support. The encapsulation of POMs in magnetic particles has been shown to increase their structural stability and accessibility to active sites, contributing to sustained catalytic performance. The magnetic properties also contribute to simplifying catalyst recovery and reuse through magnetic separation, eliminating the need for complex and energy-intensive processes. This review highlights the recent advancements in using magnetic particles as heterogeneous support for POM catalysts, emphasizing their role in stabilizing POM catalysts while improving the sustainability of the ODS process.