Preparation, Characterization, and Kinetics Model of MoCo/γ-Al2O3 Catalysts for Oxidative Desulfurization of Light Naphtha

Abstract

The subject of this work is to study the effect of pH, molybdenum content and some of the transition metals (such as Vanadium, Chromium, Manganese, Iron, Cobalt, Nickel) on the catalyst properties and performance of oxidative desulfurization (ODS). To achieve this aim, the mesoporous 5%Co10%Mo/γ-Al2O3 catalyst was prepared by incipient wetness impregnation method. Then, the as-synthesized catalysts were characterized by X-Ray Diffraction (XRD), N2-adsorption/desorption, and Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Scanning Electron Microscopy (SEM) and NH3-Temperature Programmed Desorption (NH3-TPD). The catalytic activity was measured with catalytic ODS setup. The catalyst with 10wt%Mo (as an active metal) and 5wt%Co content (as a promoter) at pH=4 represented the optimum performance for oxidative desulfurization. The 5%Co10%Mo/γ-Al2O3 has the Surface Area =170.61 m2/g, Pore Volume =0.64 cm3/g, Average Pore Diameter = 15.18nm when these parameters were increased, it led to the best operation condition of sulfur removal. The SEM images showed that the application of Co and Mo metals reaches more homogenous impregnation. The NH3-TPD result introduced the strong acidic sites of 5%Co10%Mo/γ-Al2O3. The obtained results proved that the total sulfur (all kind of sulfur in the feed) of light naphtha decreased from 160ppm to 20ppm during ODS process with the optimized catalyst. In that case, the kinetics of oxidative desulfurization of the optimized catalyst (5%Co10%Mo/γ-Al2O3) was studied. Moreover, a kinetic affinity model was utilized to determine the kinetic parameters of this reaction and the modeling results showed good agreement with experimental data.