Effectively detecting the presence of very low quantities of elements in industrial materials is a major challenge. One such example is heterogeneous catalysis where contamination and poisoning of catalysts by some elements present in small quantities adversely affect their properties and process performance.
In order to characterize these phenomena, IFPEN has developed the use of LIBSa, in partnership with the Institut Lumière Matière (Institute of Light and Matter) in Lyon. The principle is to focus a laser beam on the material to be analyzed in such a way as to apply enough energy to ablate some of the matter and convert it into plasma. The light emitted by the latter, with wavelengths characteristic of the atoms ablated, makes it possible to measure the local composition of the material and thus reconstruct a map of the elements for the sample as a whole, with a very fast measurement and visualization speed(1).
LIBS was used to locate metals such as vanadium and nickel, present in oil feeds and known to poison catalysts, even in extremely small amounts (0.001% weight).
Usually difficult to identify and visualize, their distribution in catalyst grains was obtained in a few minutes, thanks to the sensitivity of the technique(2).
Another example: the capacity of LIBS to produce a quantitative image of carbon. In some refining processes, a carbon residue known as coke can form on the surface of catalysts thereby reducing their efficiency. The use of LIBS, associated with a non-contaminating preparation methodb, made it possible to overcome the limits of conventional analysis techniques and monitor the evolution of carbon locations in the grains at various points over the time the catalyst was operating(3).
a - Laser Induced Breakdown Spectroscopy
b - Packing of grains in a copper film, then coating in a resin and mechanical polishing
(1) L. Jolivet, M. Leprince, S. Moncayo, L. Sorbier, C.-P. Lienemann, V. Motto-Ros, Spectrochim. Acta Part B 151 41–53 (2019).
(2) F. Trichard, F. Gaulier, J. Barbier, D. Espinat, B. Guichard, C.-P. Lienemann, L. Sorbier, P. Levitz, V. Motto-Ros, J. Catal. 363 183–190 (2018).
(3) L. Jolivet, V. Motto-Ros, L. Sorbier, T. Sozinho, C.-P. Lienemann, J. Anal. At. Spectrom. 35 896–903 (2020).
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