Description du sujet de thèse

One of the innovative technologies for decarbonizing the production of ammonia, the second most synthesized chemical in the world, is to break down the synthesis into two steps using nitride (MxNz) compounds that react as "reservoirs" of nitrogen: this is the synthesis of NH3 by thermochemical cycling (or CLAS for Chemical Looping for Ammonia Synthesis). The CLAS process is carried out by separately feeding a reactor with N2 (charging step) to form the nitride phase "full" of nitrogen, and then with H2 or H2O (discharging step) to produce ammonia. Under H2, the material remains a nitrogen-deficient nitride. Under H2O, the nitride is converted into oxide. Concentrated solar radiation is considered to enable the regeneration of the nitride phase from the oxide (highly endothermic step).
The thesis will be developed in two laboratories, IC2MP in Poitiers and PROMES in Odeillo. The metal nitrides will first be synthesized and characterized at IC2MP, and their behavior will be evaluated under thermochemical looping conditions on a test bench using H2 or H2O for the discharging step. Finally, for the most performant materials in the hydrolysis step, a demonstration phase of the solar process will be carried out at the PROMES laboratory using a 1.5 kWth concentrator.

Contexte de travail

The thesis work is part of the SolAmmonia project, selected under the CNRS 80 PRIME 2025 program. The PhD student will work under the co-supervision of two CNRS research directors, Nicolas Bion at IC2MP and Stéphane Abanades at PROMES.

IC2MP is a joint research unit of the CNRS (Chemistry Institute) and the University of Poitiers, comprising approximately 250 people, including about a hundred researchers. The project will be carried out within the team Du Site Actif au Matériau Catalytique (SAMCat), composed of 30 researchers, specialized in the design and physicochemical characterization of catalytic and electrocatalytic materials for energy (biofuels, e-fuels, fuel cells, electrolysis, etc.) and environmental (water and air pollution control, etc.) applications. The decarbonization of ammonia production has been studied within the team for about a decade through thermo- and electro-catalytic technological pathways.

The PROMES laboratory in Odeillo (CNRS Solar Furnace) is located in the Pyrénées-Orientales at an altitude of 1600 m, 100 km from Perpignan, 20 km from Spain, and 40 km from Andorra. PROMES is a CNRS research unit (UPR 8521) affiliated with the Engineering Institute and partnered with the University of Perpignan via Domitia (UPVD). The laboratory is spread across three sites: Odeillo-Font Romeu (CNRS 1 MW Solar Furnace), Targasonne (Thémis, 5 MW tower power plant, site of the Pyrénées-Orientales Departmental Council), and Perpignan, Tecnosud. The laboratory brings together about 150 people from the CNRS and UPVD around a unifying theme: solar energy and its utilization as a source of energy and high temperatures. The work will be conducted within the Solar Fuels team at Odeillo Font-Romeu, which develops activities focused on the production of new energy vectors and materials through thermochemical processes.

Contraintes et risques

Risks Associated with Handling Gaseous Dihydrogen and Ammonia