Electron Microscopy Characterization of Crystalline Nanostructures Present in Asphaltene

The main aim of the present work was to characterize the crystalline particles contained in asphaltene obtained from Mayan crude oil and evaluate their influence on the asphaltene microstructure. Low-vacuum scanning electron microscopy (LV-SEM) and transmission electron microscopy (TEM) techniques, such as high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM), and high-angle angular dark field (HAADF), were used as well as energy-dispersive X-ray spectroscopy (EDS) in both scanning electron microscopy (SEM) and TEM and Fourier transform infrared spectroscopy (FTIR) with this aim. The results show the presence of elements, such as Co, Cr, Mn, and Bi, identified by EDS, crystalline nanoparticles in the range of 1-150 nm, constituted basically by aluminosilicates, and particles of Fe2O3, Fe3O4, and ZnO2. Earlier reports indicate an even distribution of the elements in the asphaltene and graphitization and graphite-like particles. This work shows unequivocally that graphitization occurs around Cr and Zn particles and not around Fe oxide nanoparticles.