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Evaluation by Electron Microscopy of Chemical Changes in Spent HDT Catalysts

Abstract:

Scanning Electron Microscopy with an X-ray detector for microanalysis (EDX) and mapping is a powerful tool for the chemical characterization of materials. For this reason, it was used to determine the composition and distribution of the major elements in a spent catalyst, used empleado, utilizado in a venezuelan hydrotreatment unit (HDT), as well as the changes generated by subjecting the catalyst to different oxidizing, carbiding, and nitriding environments. In this way, an important decrease in the content of certain polluting elements such as S, could be evidenced. An increase in the content of C and the N fixation, was also observed when the catalyst was subjected to carbiding or nitriding environments. Additionally, it was possible to visualize the association of different chemical elements that would be interacting, such as Fe-Mo-S, Mo-S, Fe-P, and V-N, as well as their bkp_redispersion. All this allowed us to establish some causes of catalyst deactivation and to propose the formation of new active phases that could improve the catalyst response.