Synthesis and Characterization of Hexamethylenediammonium Thiometallates as Precursors of MoS2 and WS2 Catalysts: In situ Activation During HDS of DBT

Abstract

Hexamethylenediammonium thiometallate (HeDaT) of molybdenum and tungsten were synthesized using the aqueous solution method. This method improved significantly the yield of the catalysts. The HeDaT precursors were in situ activated during the hydrodesulfurization (HDS) of dibenzothiophene (DBT) generating MoS2 and WS2 catalysts. To characterize the precursors Fourier Transform Infra Red (FTIR), Ultraviolet (UV-Vis) and Nuclear Magnetic Resonance (H-1 NMR) spectroscopy techniques were used to determine their chemical structures. In addition, thermal analysis (TGA-DTA) were performed to study the fragmentation and decomposition behavior of their molecular structures. Catalysts were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) which showed the shapes of the particles and the characteristic fringes of the layered MoS2 and WS2 phases, respectively. Specific surface areas were determined by the BET method with values of 5 and 19 m 2/g with type I and IV adsorption-desorption nitrogen isotherms for both catalysts. The X-ray diffraction study showed poorly crystalline catalysts with weak (002) intensity for the MoS2 and a better-defined (002) reflection for the WS2.