Caracterização de frações segregadas de catalisadores de equilíbrio de FCC por microscopia eletrônica de varredura e transmissão

Abstract

In the present study, two FCC equilibrium catalysts (e-cat) were fractionated by density, each generating 4 fractions that represent increasing levels of particles density and contamination. The eight samples were characterized by X-Ray Fluorescence Spectroscopy (XRF), Nitrogen Physisorption, X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) combined with Energy Dispersive X-Ray Spectroscopy (XEDS) and Transmission Electron Microscopy (TEM) combined with XEDS and Electron Diffraction. An image analysis methodology was developed and allowed the realization of a quantitative visual characterization of the elements of interest based on the SEM/XEDS mappings. The XRF, XRD and textural analyses indicated that the density separation was successful and that the contaminating metals are more concentrated in the denser fractions, which also presented greater deterioration of zeolites crystal structure. The SEM/XEDS analyses revealed the existence of particles populations with different compositions regarding the Si/Al ratio, making it possible to relate the type of catalyst with its level of contamination by Ni. A strong interaction between Ni and Al was observed by STEM/EDS and electron diffraction analyses, possibly due formation of a nickel aluminate.