High-performance NiMoS hydrodesulfurization catalysts by one-pot hydrothermal synthesis using Ni(acac)2 for sulfur-free liquid fuels

Abstract

A straightforward hydrothermal synthesis of NiMoS active phases loaded on SBA-15 was attempted. We initially prepared a catalyst by impregnating metal precursors sequentially onto SBA-15 and the subsequent hydrothermal treatment with sublimed sulfur. To obtain the one-pot catalyst, we performed the hydrothermal treatment of a mechanical mixture containing metal precursors, sublimed sulfur, and SBA-15. The catalysts were characterized by powder X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, N2 adsorption-desorption study, and high-resolution transmission emission spectroscopy. Compared to impregnation-assisted synthesis, the one-pot synthesis promoted the generation of dispersed shorter MoS2 slabs with desirable average stacking number, i.e., increased number of edge and rim sites. Therefore, the one-pot catalyst enabled the ultra-deep sulfur removal (~100%) in the dibenzothiophene hydrodesulfurization. Unlike Ni(acac)2, the utilization of Ni(NO3)2 inhibits the sulfidation of molybdenum and the dispersion of MoS2 layers, decreasing the hydrodesulfurization activity. The one-pot catalyst was able to achieve ~80% sulfur removal even after six consecutive catalytic runs under batch reactor conditions (320 °C, 6 MPa (H2), 500 ppmw S, 100 mg (mcat)) due to the persistent stability of NiMoS active phases.