Unsupported NiMo catalysts prepared from a novel partly-sulfided complex precursor for dibenzothiophene hydrodesulfurization

Abstract

A new partly-sulfided Ni–Mo dimetallic complex, [Ni(H2O)6][Mo2O2S2(edta)]·2H2O (edta = ethylenediaminetetraacetate) was synthesized. The complex was decomposed either in situ during the course of a dibenzothiophene (DBT) hydrodesulfrization (HDS) test or ex situ through sulfidation by H2S/N2 and two unsupported catalysts were obtained. These two catalysts and reference catalyst were characterized by XRD, BET and HRTEM. Textural and catalytic properties of these NiMo catalysts were strongly influenced by the nature of the precursor and the activation procedure. The introduction of edta ligand in the complex precursor resulted in the dispersion increase of nickel phases in these two catalysts. For these two catalysts, the ex situ activation method led to higher surface area, bigger pore volume, lower number of MoS2 layers and shorter MoS2 slabs than that led by the in situ activation method. The use of ex situ activation method led to a poor HDS activity and high hydrogenation selectivity while using in situ activation method, a net increase in HDS activity and initial rate constant was observed.