MOF-derived NiMoS hollow sphere for efficient hydrodesulfurization: Effects of composition and morphology of active phase of NiMoS catalysts

Abstract

The rational modulation of bimetallic intimately synergistic unsupported catalysts is the essential approach for efficient hydrodesulfurization (HDS). Herein, we have successfully produced NiMoS hollow spheres (H-NiMoS) by the Ni-MOF-engaged strategy using Ni metal–organic framework (Ni-MOF) as a precursor. The Ni-MOF serves as a landing site for vertically oriented MoS₂ nanosheets and also acts as a nickel promoter for inducing the formation of the NiMoS active phase. The H-NiMoS catalyst achieves three-dimensional self-assembly of MoS₂ nanosheets on hollow spheres, displaying a higher specific surface area (105 m²·g⁻¹) compared to pure MoS₂ (52 m²·g⁻¹). The H-NiMoS catalyst produces vertical MoS₂ with low stacking number (2–3 layers) and short slab length (2–4 nm), thus providing a large number of “rim” sites for HDS reaction. As expected, the H-NiMoS catalyst exhibits efficient HDS activity with 99.8 % conversion of dibenzothiophene (DBT) and 93.0 % conversion of 4,6-dimethyldibenzothiophene (4,6-DMDBT), as well as HDS selectivity that S_HYD/DDS(DBT) = 1.3 and S_{HYD/DDS(4,6-DMDBT)} = 3.2. Consequently, the Ni-MOF-engaged strategy of fabricating MoS₂ nanosheets with vertically oriented structures by using Ni-MOF precursors provides significant guidance for improving the activity and HYD selectivity of conventional HDS catalysts by exposing more “rim” sites.