Slurry phase hydrocracking of vacuum residue in the presence of presulfided oil-soluble MoS2 catalyst

Abstract

Abstract Herein, a simple method for the preparation of presulfided oil-soluble MoS2 catalysts was proposed. The catalyst precursor, cetyltrimethyl ammonium heptamolybdate (CTATTM) was easily synthesized by dissolving ammonium tetrathiomolybdate in an aqueous solution containing excess cetyltrimethyl ammonium\xa0bromide, which could be directly dissolved in a vacuum residue (VR). The obtained catalyst was evaluated in slurry phase hydrocracking of VR at 410\u202f°C with an initial H2 pressure of 10\u202fMPa for 1\u202fh. It showed remarkable hydrocracking activity, with a reduction of the resin content from 25.21 to 3.54\u202fwt% and of the C7-asphaltene content from 6.82\u202fwt% to almost zero. With using the catalyst, as the yield of the liquid product increased from 75.03 to 96.43\u202fwt%, yields of the coke and gas would be only 0.19, and 3.38\u202fwt%, respectively, significantly lower than the values of 14.05, and 10.92\u202fwt%, respectively, obtained without using the catalyst. Moreover, with increasing Mo content, hydrodemetalization conversion increased from 42.5 to 83.4\u202fwt%, while hydrodesulfurization conversion increased from 21.6 to 59.2\u202fwt%. In addition, a higher initial H2 pressure over 10\u202fMPa can more efficiently promote the conversion of VR to light oil products with a significantly lower formation of coke and gas than the cases under conditions below 10\u202fMPa. Multiple techniques, including X-Ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Fourier-transform infrared spectroscopy (FT-IR), were employed to determine a plausible correlation between the structure and performance. The CTATTM precursor shows good solubility and stability in heavy oil, leading to easy formation of small MoS2 particles with stacking numbers of 1 and 2, and slab lengths of 5–11\u202fnm. This presulfided oil-soluble MoS2 catalyst with good hydrocracking activity for VR shows great\xa0potential for further industrial applications.