Hydrodesulfurization catalysts prepared by two methods analyzed by transmission electron microscopy

Abstract

Samples of molybdenum sulfide, cobalt sulfide and mixtures in atomic ratios r = Co/(Co + Mo) of 0.0, 0.3, 0.5, 0.7, and 1.0 were prepared by two different methods, homogeneous sulfide precipitation (HSP) and impregnated thiosalt decomposition (ITD). Samples were observed by high-resolution electron microscopy using imaging and diffraction modes. Both preparation methods present the “rag structure” typical of MoS 22H with some structural differences between them. The average number of layers (n) in molybdenum disulfide crystals is about the same in both preparation methods, while the average length (L) of the molybdenum disulfide crystallites obtained by HSP is larger than that of those obtained by ITD. The particle size is smaller for ITD samples. The presence of cobalt does not greatly modify the number of layers of the MoS 22H stacks in mixed samples. An increase in the intracrystallite disorder is observed.