Comparative Studies of Carbon Nanomaterial and γ-Alumina as Supports for the Ni-Mo Catalyst in Hydrotreating of Gas Oils

Carbon nanohorns (CNH), other carbon particles (OCP), fine fractions of other carbon particles (OCPf), carbon nanotubes (CNT), and gamma-alumina (gamma-Al2O3) were utilized as support materials for the Ni-Mo catalyst in this study to test the influence of the support on hydrotreating efficiency using light gas oil (LGO) and identify the cause of disparity in activity from these various catalyst supports. OCP and OCPf are the main byproducts obtained during the production of CNH. The influence of the support on the hydrotreating catalyst is significant and includes enhancement of textural properties, active phase dispersion, and catalyst reducibility. The hydrodenitrogenation activities of all of the different supported catalysts with light gas oil are presented and correlated with their physicochemical properties. Among all of the carbon-supported catalysts used, the NiMo/ CNH catalyst exhibited outstanding physicochemical properties, and as such, its hydrodesulfurization activity of 89% dominated that of NiMo/OCPf (78%), NiMo/OCP (67%), and NiMo/CNT (73%) catalysts. The pore volume, pore diameter, and surface area of the NiMo/CNH catalyst was 0.42 cm(3)/g, 10.9 nm, and 350 m(2)/g, respectively. The percentage metal dispersion of the NiMo/CNH catalyst was 8.0% and was about twice that of the NiMo/OCP f and NiMo/CNT catalysts. X-ray absorption spectroscopy (XAS) analysis confirmed that the carbon-supported catalysts exhibited a distorted octahedral Mo coordination environment, whereas the NiMo/gamma-Al2O3 catalyst exhibited a mixture of octahedral and tetrahedral Mo environment. From XAS results, it was apparent that the possession of a Mo octahedral coordination environment does not always translate to attainment of highest hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) activities.

Automated summary

This study investigated the influence of different support materials on the efficiency of hydrotreating catalyst with Ni-Mo. It was found that NiMo/CNH catalyst exhibited outstanding physicochemical properties, leading to superior hydrodesulfurization activity compared to NiMo/OCPf, NiMo/OCP, and NiMo/CNT catalysts. X-ray absorption spectroscopy analysis revealed that a distorted octahedral Mo coordination environment in carbon-supported catalysts did not always correlate with higher hydrodesulfurization and hydrodenitrogenation activities.