Nano-particle metal sulfides for ultra-deep HDS of diesel fuels

Background Developing the hydrodesulfurization (HDS) catalysts with the super high activity has been a challenging project for achieving the ultra-deep desulfurization of diesel fuels [1]. Here, we report a surfactant-assisted co-precipitation method for the preparation of unsupported Ni-Mo-W sulfide catalysts. The catalysts exhibit super high HDS activity for the real diesel up to 7.5 times excelling the conventional commercial catalysts. The sulfur level of the diesel fuels can be decreased to less than 1 ppm from 1400 ppm under the conventional operating conditions. Results A series of Ni-Mo-W sulfide catalysts were prepared with the different solvents and surfactants to investigate the effect of the catalyst properties on the HDS activity of Ni-Mo-W sulfide catalysts. The HDS catalytic activities of the sulfide catalysts were evaluated in a flow fixed-bed micro reactor. The sulfur content of the desulfurized diesel is reduced to less than 1 ppm from 1400 ppm. A model fuel containing 4,6-DMDBT in decalin was used to test the HDS activity and to calculate the 4,6-DMDBT HDS reaction kinetic parameters for the catalysts. The catalysts also exhibited a higher intrinsic HDS activity. It is found that the overall rate constants for HDS reaction of the catalysts showed about 3.0 times higher than that of the commercial catalyst. The catalysts were characterized by XRD, TEM, TPR, and XPS. The catalysts exhibit a uniform distribution of nanoparticles with the size of about 20 nm and possibly forms some composite sulfide active phases with the average slab length of 2-5 nm and the average stack layer number of 4-8. Justification for acceptance The nano composite sulfide catalysts were synthesized through using a special method. These catalysts demonstrated an excellent HDS activity for the real diesel fuels, which is about 7 times higher than the conventional commercial catalysts, and the ultra-low sulfur diesel (< 1 ppm sulfur) can be obtaine