In situ synthesis of MoS2 nanoflakes within a 3D mesoporous carbon framework for hydrodesulfurization of DBT

Abstract

Two new mesoporous carbon-supported Co-Mo hydrodesulfurization catalysts with different Co contents have been successfully prepared by one-step vacuum freeze-drying, followed by calcination under a nitrogen atmosphere and washing. Evans-Showell polyoxometalate (NH4)6[Co2Mo10O38H4]·7H2O was used as the Co-Mo precursor instead of the conventional precursors, and the obtained catalysts were structurally characterized by various technologies, including X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, H2 temperature programmed reduction, CO temperature programmed desorption and low temperature N2 adsorption-desorption isotherm. The results show that MoS2 particles (4.6 nm and 4.5 slabs) are homogeneously dispersed in the mesoporous carbon framework with a narrow pore size distribution centered at 3.7 nm. The catalysts were evaluated by the hydrodesulfurization of dibenzothiophene, and the results show that the dibenzothiophene conversion, overall pseudo-first order rate constant and turnover frequency can reach 95 %, 5.4 × 10−6 mol g−1 s−1 and 6.1 × 10−3 s−1 at 300 °C, respectively, indicating higher catalytic activity than previously reported catalysts. The higher proportion of the CoMoS active phase can account for the higher catalytic activity. By using in situ-produced sodium chloride crystals and thiourea as hard templates and sulfidizing agents respectively, this study opens a new avenue for the simple and environmentally friendly preparation of hydrodesulfurization catalysts with the synchronization and riveting of MoS2 nanoflakes and 3D mesoporous carbon frameworks.