Research on Deep Eutectic Solvents for Fuel Desulfurization: Methods, Mechanisms, and Emerging Trends

With increasing environmental concerns and stricter sulfur-emission regulations, efficient removal of sulfur-containing compounds from fuels has become a critical issue. Traditional hydrodesulfurization (HDS) faces challenges, including high energy consumption, limited efficiency for refractory sulfur compounds, and the need for severe operating conditions. Therefore, alternative desulfurization methods using novel solvents and green materials have gained interest. Among these, deep eutectic solvents (DESs) are particularly promising due to their tunable physicochemical properties, low toxicity, biodegradability, and excellent extraction capabilities. Unlike previous reviews that primarily emphasize experimental performance comparisons of DESs, this review provides a mechanism- and computation-driven perspective on DES-based fuel desulfurization, with particular emphasis on mechanistic elucidation through the integration of experimental investigations and multiscale computational approaches across different desulfurization technologies. It first introduces the definition, classification, and key physicochemical properties of DESs and their influence on desulfurization performance. Experimental and computational approaches were used to elucidate desulfurization mechanisms, including multiscale simulations and advanced characterization techniques. Finally, emerging research trends in DESs research, such as the design of composite systems, multifunctional development, and strategies for green and sustainable applications, are discussed.