Sustainable desulfurization through coupled extraction-catalytic oxidation strategy: Mechanisms, materials, and process intensification

In response to the imperative for sustainable energy and environmental protection, ultra-deep desulfurization of fuels poses a critical challenge. Conventional hydrodesulfurization and emerging non-hydrogenation techniques face limitations in efficiency, economic viability, and ecological sustainability, particularly for refractory sulfur species. Among alternatives, extractive catalytic oxidative desulfurization (ECODS) has emerged as a prominent approach by integrating catalytic oxidation and liquid-phase extraction under mild conditions. It employs green solvents such as ionic liquids and deep eutectic solvents, along with recyclable heterogeneous catalysts (e.g., polyoxometalates and metal-organic frameworks). This review examines the reaction mechanisms-both radical and non-radical pathways-underpinning ECODS, alongside material design strategies for catalysts and sustainable solvents. We further evaluate process parameters and techno-economic factors critical for scalability. ECODS demonstrates high efficiency (typically >97% sulfur removal) and robust reusability, in alignment with green chemistry principles through minimized energy input, avoidance of hazardous reagents, and emphasis on atom economy and recyclability. This work underscores the potential of ECODS as a sustainable pathway toward ultra-clean fuels (sulfur content < 10 ppm) and outlines future directions for catalytic innovation and industrially compatible process intensification.