Fast electron migration for efficient sodium desulfurization by producing activated sodium metal microspheres with large reaction interfaces

Abstract

Achieving a highly efficient desulfurization of heavy feed oils using sodium metal remains challenging owing to its restricted reaction interface. Herein, membrane emulsification technology was adopted to produce monodisperse activated sodium metal (aNa) microspheres with considerably enhanced reaction interfaces for efficient desulfurization of benzothiophene (BT) without requiring a catalyst. By regulating membrane emulsification parameters, the molten sodium into the model oil using a membrane device, optimized aNa microspheres with a particle size of 27.71 μm and a large specific surface area of 2.17 × 10⁵ m²·m⁻³, which was 50–100 times larger than that of microspheres prepared via mechanical agitation, were obtained. On the basis of the rich reaction interfaces, the efficient sodium desulfurization would proceed via Coulomb-like explosion initiated by aNa to form solvated electrons and cleavage of the C–S bond at one end to generate C⁺, which trigger the final cleavage of the C–S bond in BT under the continued attack of the fast C⁺ electron cloud, together with the generation of styrene and sodium sulfide. With the assistance of hydrogenation, fast and efficient benzothiophene desulfurization was achieved with a desulfurization efficiency of > 90 % within 15 min under the optimized reaction conditions, i.e., reaction temperature, pressure, and Na/S ratio. This study provides a fast and efficient sulfur removal technology to replace conventional catalytic hydrodesulfurization.