A novel catalyst of nickel-loaded graphene decorated on molybdenum-alumina for the HDS of liquid fuels

Abstract

In the process of hydrodesulfurization (HDS) the activation of the dibenzothiophene (DBT) occurs on the catalysts’ active sites, in addition to the promoter. The distribution of both catalyst and promotor has a significant influence on the HDS activity and, along with improved nanoparticle distribution, more active sites will be available for the DBT molecules to be adsorbed and desulfurized. In this work the idea is to load the Ni promoter on graphene and the Mo catalyst on alumina separately, and then the obtained Ni/graphene will be loaded on Mo/alumina. The obtained alumina-molybdenum loaded with Ni nanoparticles on graphene (AlMoGNi) was assessed for the HDS of DBT. The characterization of the synthesized materials was conducted by using a surface area analyzer, temperature programmed analysis, an X-ray powder diffraction analyzer, scanning electron microscopy with an energy-dispersive X-ray spectroscopy, a transmission electron microscope, inductively coupled plasma and Fourier transform Infra-red spectroscopy. The catalytic efficiency of the catalysts was investigated in a reactor at a temperature of 573 K and under hydrogen pressure of 53 bar. The decalin was utilized as a fuel with 600 parts per million sulfurs (ppm-S). With the use of an AlMoGNi catalyst, the concentration of sulfur was reduced in the tested fuel to (9 ppm-S, 99% conversion) compared to about (95 ppm-S, 84% conversion) using the catalyst without graphene. The superior performance of the AlMoGNi catalyst can be explained by its textural properties, surface acidity, and nanoparticle dispersion. The hydrodesulfurization over the AlMoGNi catalyst occurred through both hydrogenolysis and hydrogenation desulfurization pathways.