Jae Hyun Koh

Preparation of CoMoS catalysts for hydrodesulfurization using methylacetoacetate as a chelating agent

CoMoS/Al2O3 catalyst, which was prepared using Co(MeAA)2·2H2O as a new Co precursor, showed activity for hydrodesulfurization (HDS) higher than that of conventional catalysts, which were prepared using Co(NO3)·6H2O as a Co precursor and/or by adding ethylene-di-amine-tetra-acetic acid (EDTA) as a chelating agent. Catalyst of a similar activity was also obtained simply by impregnating a conventional CoMo/Al2O3 catalyst with an aqueous solution of methylacetoacetate (MeAA) followed by drying and sulfidation. The added MeAA reacted with Co to produce Co(MeAA)2·2H2O on the catalyst surface during impregnation step, such that the resulting catalyst became similar to one prepared by direct impregnation with Co(MeAA)2·2H2O. The in-situ synthesis of Co(MeAA)2·2H2O on the catalyst surface was advantageous over the method of directly adding the Co precursor to the impregnation solution because the former method did not use a basic material, which was required for the synthesis of the Co precursor. Furthermore, MeAA was soluble in water, whereas Co(MeAA)2·2H2O had to be dissolved in an organic solvent, e.g., 1,4-dioxane. The Co species in the MeAA-added catalysts were sulfided at temperatures higher than those of conventional catalysts, and consequently the former catalysts contained greater amounts of the HDS-active CoMoS phase than the latter.