Fabrication of three-dimensional MoS₂-graphene hybrid monoliths and their catalytic performance for hydrodesulfurization

A simple process to synthesize three-dimensional molybdenum disulfide-graphene monolithic catalysts (3D-MoS₂-G) was developed. 3D-MoS₂-G hybrid monoliths were fabricated by a combined hydrothermal self-assembly and freeze-drying treatment, in which ammonium tetrathiomolybdate and graphite oxide were used as starting materials. The structure and morphology of the samples were characterized by X-ray diffraction, Fourier transform infrared spectrometry, Raman spectrometry, field emission scanning electron microscopy, transmission electron microscopy and nitrogen adsorption. The catalytic performance of the hybrid monoliths was investigated by evaluating the activity for the hydrodesulfurization (HDS) of carbonyl sulfide (COS). In addition, the influence of microwave irradiation on the catalytic property of the 3D-MoS₂-G monoliths was also investigated. It is demonstrated that after microwave irradiation the 3D-MoS₂-G monoliths show an excellent activity for COS hydrogenation compared with the traditional MoS₂/γ-Al₂O₃ catalyst prepared by impregnation-sulfidation. The 3D-MoS₂-G-160M monolith hydrothermally synthesized at 160℃ exhibits the highest COS conversion of 100% at a relatively low temperature (260℃) for the HDS reaction. The superior performance of the 3D-MoS₂-G-160M catalyst can be ascribed to the unique hybridized structure of the MoS₂ nanoparticles uniformly dispersed on graphene sheets in the monolith.