In situ synthesis of the MoS2–GO catalyst and unveiling its potential for deep hydrogenation desulfurization

Abstract

The MoS₂ catalyst shows great potential in deep hydrodesulfurization (HDS) but is limited by high metal usage and low active site utilization. A MoS₂–GO composite catalyst with trace amounts of graphene oxide (GO) was synthesized via an in situ solvothermal method. Owing to its high polarity, deionized water acts as an effective dispersant for GO, ensuring uniform dispersion while preserving its sheet-like morphology. The Mo precursor, bearing organic functional groups, is homogeneously anchored onto the oxygen functionalities of GO sheets, resulting in a densely packed monolayer MoS₂ structure with abundant, highly exposed HDS edge sites across the layered GO surface. Combined X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) analyses reveal that MoS₂ forms a heterostructure with GO through interactions between S atoms and the surface oxygen functionalities of GO. In the HDS reaction, it achieves 98.3% dibenzothiophene (DBT) conversion at 280 °C and exhibits high hydrogenation desulfurization (HYD) selectivity (S_(HYD/DDS) up to 12.8). Notably, it demonstrates excellent activity for sterically hindered 4,6-dimethyldibenzothiophene (4,6-DMDBT, 80.7% conversion at 300 °C) and a high HYD pathway selectivity (S_(HYD/DDS) up to 13.9). Raman spectroscopy coupled with DFT calculations reveals that the MoS₂–GO catalyst features extensive Mo–S–O(GO) electron-transport networks, which facilitate H₂ dissociation and drive continuous hydrodesulfurization of sulfur-containing species. This study provides insights into the preparation of heavy oil hydrocracking catalysts and the regulation of hydrogenation pathway selectivity.