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A PhD student (H/F) for the study of the influence of the OXYgen transport properties of cerium oxide-based 3D architectures on their RADiative properties : toward the improvement of hydrogen production with concentrated solar energy (OXYRAD)

This offer is available in the following languages:
Français - Anglais

Date Limite Candidature : jeudi 2 juin 2022

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General information

Reference : UMR6607-MICAUD-007
Workplace : NANTES
Date of publication : Thursday, May 12, 2022
Scientific Responsible name : Benoit ROUSSEAU
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2022
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly

Description of the thesis topic

OXYRAD, is a research project “80 prime” funded by the Mission for Transversal and Interdisciplinary Initiatives (MITI ) which aims to support interdisciplinary program within CNRS. The goal of OXYDRAD is to improve the production rate of dihydrogen (H2) from a thermochemical cycle where cerium oxide - CeO2 - is initially thermally reduced (1400° C) by concentrated solar radiation. In a second step, as-reduced CeO2 is re-oxidized in the presence of water vapor (1000°C) generating then H2. To improve the production rate requires, among others, a better understanding of the impact of oxygen mobility on the radiative properties at high temperatures, in particular within porous architectures of CeO2, obtained by robocasting. However, to date, the thermal radiative properties of CeO2 are only known at room temperature and the oxygen transport properties are studied on powders, the resulting texture being far from those of advanced porous architectures. OXYRAD thus intends to establish, at high temperature, the link between the transport of oxygen, the texture imposed by the elaboration and the thermalradiative behavior of the porous architectures of CeO2.

Work Context

The European requirement to achieve carbon neutrality by 2050 implies the implementation of new industrial energy production processes, independent of conventional fossil resources. This imperative thus applies to the production of dihydrogen (H2) which could represent, according to several scenarios, between 10 and 23% of total European energy consumption compared to 2% today. However, the major part of industrial dihydrogen (95%) is obtained from hydrocarbons (gas, oil, coal) which explains the current challenges around the establishment of an industrial sector where this energy vector must be produced by carbon-free pathways. As an alternative to water electrolysis, the use of two-step thermochemical cycles to produce hydrogen is showing great promise. The Swiss company Synhelion, a spin-off from the Swiss Federal Institute of Technology in Zurich (ETH), has thus developed innovative chemical reactors, where cerium oxide (CeO2) based- open-cell foams are thermally reduced under low partial pressure of oxygen at 1400°C then re-oxidized in the presence of steam at 1000°C, allowing the production of dihydrogen. Heat is supplied here by solar concentration. To make this route economically viable, it is necessary to have an overall energy efficiency of 20%, equivalent to that of electrolysis, compared to 5% today. Several challenges need to be overcome: (i) smartly depositing concentrated solar radiation throughout the volume of the CeO2-based porous ceramic in order to have an isothermal temperature field for chemical reactions while minimizing radiative losses (ii) guaranteeing a surface solid/fluid exchange maximized, which favors re-oxidation kinetics (iii) promoting the creation of oxygen vacancies in the largest amount of CeO2 available during the first reduction step.

Constraints and risks

The PhD student will start his thesis in Limoges for the first 12 months and will continue in Nantes for the last 24 months.
-Use of heating laser.

Additional Information

The Ph-D student will have a master degree level from engineering school or University in materials science and/or thermal science. He will have a pronounced interest for subjects around the energy transition (green production of H2), in particular when concentrated solar energy.

Ability to write in French (C1) and English (B2), to make presentations in French (C1) and English (B2)
Know-how: pronounced taste for experimental developmenst (electrical and/or thermal and/or optical)
Soft skills: autonomy, sociability (work with different teams on two sites), sense of responsiveness

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