Plans d'accès
Webmail
Accueil > A propos du LPP > Communication > Actualités archivées > 2023 > Edmond Baratte defended his PhD "An experimental and numerical investigation of fundamental mechanisms in CO2-CH4 plasmas"
Edmond Baratte defended his PhD "An experimental and numerical investigation of fundamental mechanisms in CO2-CH4 plasmas"
Toutes les versions de cet article : [English] [français]
On March 17, 2023, Edmond Baratte defended his PhD "An experimental and numerical investigation of fundamental mechanisms in CO2-CH4 plasmas".
Abstract :
Global warming, a major challenge of this century, is caused by greenhouse gas emissions from human activities. It is necessary to control these emissions. Recycling CO2 into higher value-added products is one of the solutions. One way of recycling CO2 is the dry reforming of methane by plasma, (CO2 + CH4 to 2CO + 2H2), which produces a mixture of CO and H2 usable in the Fischer-Tropch reaction (nCO +2n+1 H2 to CnH2n+2 + nH2O) to produce heavy carbon chains with high energy density. Cold plasmas are promising to achieve this at low energy cost : the targeted energy deposition in the molecule limits the energy loss in gas heating. Cold plasmas of CO2:CH4 are still very poorly understood because of their complexity : they combine complex physical phenomena with extensive organic chemistry. Moreover, because of the application interest, many studies use catalysts and inhomogeneous reactor configurations (by the type of plasma discharge or reactor geometry), making it difficult to understand the underlying physics. Optimizing applications requires a better description of the fundamental plasma mechanisms. The question guiding this work is therefore : what are the physical and chemical phenomena leading to the conversion in a CO2-CH4 plasma ?
Low pressure glow discharge and radio frequency plasmas are used to perform a fundamental study allowing systematic model/experiment comparisons. The chemical kinetics of the plasma is studied in a low pressure glow discharge allowing to measure easily the electric field, the gas temperature and the electron density. Gas composition and conversion rates are measured by IR absorption spectroscopy. A modeling of the chemical kinetics of the glow discharge is carried out using the kinetic solver LoKI, initially by taking into account only the molecules with at most 1 carbon atom. The numerical results are systematically compared to the measurements taken to constrain the kinetic scheme. Thanks to a good agreement obtained over a wide range of pressures, flows and initial mixtures, the main reaction paths are highlighted. Excited species, often neglected in the analysis of CO2-CH4 plasmas, are shown to play an essential role, in particular the O(1D) state. Taking into account O(1D) highlights new reaction pathways, usually replaced by the complex chemistry of C2H species. A similar study is carried out by following the temporal evolution of the densities in a radiofrequency discharge which this time allows to follow the temporal evolution of the chemistry until reaching a stationary state. The model must then be completed with molecules containing 2 carbon atoms. The influence of O(1D) is confirmed, as well as the less preponderant role of C2H compared to the literature. The CH3 + O(1D) reaction appears to be critical. The role of surfaces also appears essential to explain some processes. Finally the vibrational kinetics of CO2, crucial to limit the energy cost of dissociation, is studied in 5ms plasma pulses. CH4 and its dissociation products (H2, H2O, H) strongly decrease the vibrational excitation of CO2, but that of CO is on the contrary increased in some cases. Again, the involvement of O(1D) in vibrational excitation processes is suspected.
Jury :
Dr. Erik Johnson, Dir. de recherche CNRS, Ecole Polytechnique, Examinateur
Dr. Gilles Cartry , Professeur, Aix-Marseille Université, Rapporteur
Dr. Carlos Pintassilgo Associate professor, University of Porto, Rapporteur
Dr. Simon Dap, Professeur associé, Université Paul Sabatier, Examinateur
Dr. Carmen Guerra-Garcia, Assistant Professor, MIT, Examinateur
Dr. Christophe Laux, Professeur, CentraleSupelec, Examinateur
Dr. Paolo Tosi, Associate professor, University of Trento, Examinateur
Dr. Olivier Guaitella, Ing. de recherche, Ecole Polytechnique, Directeur de thèse
Dans la même rubrique :
- 1ère Journée scientifique HelioSwarm France (LPP, 5 mai 2023, Paris)
- Le champ magnétique solaire vu en stéréo
- Le LPP au congrès général des 150 ans de la Société Française de Physique
- Ondulations à la surface du choc terrestre lorsque le vent solaire souffle à forts nombres de Mach
- Journée à la mémoire de Nicole Cornilleau le 25 septembre
- Vincent David a soutenu sa thèse "Multiscale solar wind turbulence : from theory to observations"
- Pauline Simon a soutenu sa thèse "D’une pression isotrope à l’anisotropie de pression dans les plasmas spatiaux turbulents : Investigation analytique, numérique et observationnelle"
- Collaboration interdisciplinaire autour de la turbulence d’ondes
- BepiColombo/Mio détecte les premières ondes électromagnétiques haute fréquence dans l’environnement plasma de Mercure
- Nomination de Catherine Krafft comme Membre Sénior de l’Institut Universitaire de France (IUF)
- Fête de la Science 2023
- Des chercheurs du LPP ont participé à deux ouvrages pour mieux faire connaître la physique
- Pierre Morel a soutenu son HDR « Contribution à l’étude des instabilités, de la turbulence, et du transport, dans les plasmas magnétisés »
- COMHET : une nouvelle étape dans la collaboration LPP/SAFRAN sur les propulseurs électriques
- Jean-Paul Booth reçoit le prix Nishizawa 2023
- Chen Xing a soutenu sa thèse sur le rôle de la reconnexion magnétique dans l’évolution des tubes de flux magnétique des éruptions solaires
- Sae Aizawa a été recrutée comme chargée de recherche CNRS au LPP
- Tarek Ben Slimane a soutenu sa thèse "Investigation of the Optical Emission of Hall Effect Thrusters using Collisional Radiative Models, PIC Simulations, and Machine Learning"
- Hang Yang a soutenu sa thèse "Multi-periodic and random mode of Atmospheric Pressure Plasma Jets and their interactions with liquid and biological targets"
- Edmond Baratte a soutenu sa thèse "An experimental and numerical investigation of fundamental mechanisms in CO2-CH4 plasmas"
