Abstract

In this work the TEM characterization of ultradisperse MoS2-type solids, synthesized through the thermal decomposition of water-in-oil emulsions, was carried out in order to assess feasible active phases in novel ultradispersed catalytic systems currently employed for the conversion of heavy hydrocarbons. Ammonium heptamolybdate tetra-hydrated ((NH4)6Mo7O24.4H2O) and ammonium sulfide ((NH4)2S) were selected as precursor salt and sulfurizing agent, respectively, and dissolved simultaneously in the aqueous phase of the emulsion. A slight decrease in the average emulsion droplet size was observed when the concentration of ammonium sulfide present in the aqueous phase was low. TEM images showed the formation of typical layered MoS2 structures with different lengths. Additionally, average stacking degree values between 4 and 6 were determined for the structures. Finally, our results suggest that a low concentration of surfactant promotes the formation of stoichiometric MoS2 phases (atomic S/Mo ratio ~ 2) as well as less stacking of the structures.