Imaging of alumina supports by laser-induced breakdown spectroscopy: A new tool to understand the diffusion of trace metal impurities

Florian Trichard (1) , Florine Gaulier (2) , Jérémie Barbier (2) , Didier Espinat (2) , Bertrand Guichard (2) , Charles-Philippe Lienemann (2) , Loic Sorbier (2) , Pierre Levitz (3) , Vincent Motto-Ros (4)

1 Ablatom
2 IFPEN - IFP Energies nouvelles
3 PHENIX - PHysicochimie des Electrolytes et Nanosystèmes InterfaciauX
4 ILM - Institut Lumière Matière [Villeurbanne]

Imaging the distribution of reactive molecules in an internal diffusion-limited catalyst is of primary importance in the comprehension and modeling of these systems. Mesoporous alumina supports were impregnated with asphaltenes in a self-pressurized autoclave at high pressure (5 MPa) and high temperature (523 K). Extrudates were then analyzed by laser-induced breakdown spectroscopy (LIBS). We showed that LIBS can provide quantitative concentration maps of sulfur , nickel and vanadium in the ppm range. Processing of these maps is proposed to obtain one-dimensional profiles of the penetration of these elements. These profiles show that the penetration of asphaltenes into the catalyst support is a very complex process. These findings contribute to improving the comprehension of internal diffusion-limited processes, particularly the hy-drodemetallization (HDM) process of oil residues. This report also indicates that LIBS-based 2 imaging represents a powerful tool for quickly providing two-dimensional elemental maps over a large dynamic range, i.e., typically from ppm to tens of %, thereby opening up opportunities for innumerable applications in the field of catalysis.

Keywords: LIBS; asphaltenes; imaging; Trace elements

Domains: Physics [physics]; Chemical Sciences; Analytical chemistry

Florian Trichard, Florine Gaulier, Jérémie Barbier, Didier Espinat, Bertrand Guichard, et al.. Imaging of alumina supports by laser-induced breakdown spectroscopy: A new tool to understand the diffusion of trace metal impurities. Chinese Journal of Catalysis, 2018, 363, pp.183-190. ⟨10.1016/j.jcat.2018.04.013⟩. ⟨hal-01978484⟩