Thèse Optimisation des Systèmes Lohc Interaction Entre Composition Isomérique Cinétique et Phénomènes de Transport Lors des Cycles d'Hydrogénation - Déshydrogénation H/F - 69

Établissement : Université Claude Bernard Lyon 1
École doctorale : Chimie de Lyon
Laboratoire de recherche : IRCELYON - INSTITUT DE RECHERCHES SUR LA CATALYSE ET L'ENVIRONNEMENT DE LYON
Direction de la thèse : Valérie MEILLE ORCID 0000000322589656
Début de la thèse : 2026-10-01
Date limite de candidature : 2026-05-15T23:59:59

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Hydrogen storage in organic liquid molecules (LOHC) is the focus of many academic projects and a
few industrial developments nowadays. H2 storage and release consist of catalytic hydrogenation
and dehydrogenation, respectively. LOHC pairs such as benzyltoluene (BT) and dibenzyltoluene
(DBT) have been widely studied due to their large-scale production as heat transfer fluids. Stable
and liquid over a wide temperature range, their storage is very safe and the dehydrogenation
products are easily condensed and separated from hydrogen [1].
Nevertheless, despite the large number of projects and publications describing the use of these
compounds, it is often overlooked that these fluids are complex, composed of ortho, meta and
para isomers; and, for DBT, benzyl(benzyl)toluenes are also present, which makes the liquid
analysis very tricky [2]. Furthermore, the hydrogenated molecules, containing methylcycloalkane
groups, increase the mixture complexity by adding a cis/trans isomerism to the position isomerism.

With regard to benzyltoluene(BT)/perhydrobenzyltoluene(H12-BT), it is known that para-H12-BT is
significantly more easily dehydrogenated than its ortho- and para-isomers [3]. In his Ph.D., X. Ji
also observed for hydrogenation the most reactivity for the 2,4-DBT and the least reactivity for
the BBT in the DBT mixture. However, cis/trans reactivity is unknown and it is common knowledge
that it can have a significant impact in reaction rate, which have to be as high as possible tomaximise the speed of hydrogen recovery.
BT hydrogenation generally uses a nickel-based catalyst, whereas H12-BT dehydrogenation is
performed with platinum. Each reaction can thus lead to a different isomeric composition.
Studying the impact of this isomeric composition would be a plus for the detailed description of
the reaction kinetics, and should lead to increasing the process performance. Currently, kinetic
studies group Hx-BT isomers together as lumps (1 lump for H0-BT, 1 for H6-BT, 1 for H12-BT).