Description du sujet de thèse

Pyrolysis and oxidation of aldehydes and ketones.
Current transportation fuels are derived from petroleum and their partial replacement using renewable products derived from biomass is being considered in all industrialized countries and is on EU's agenda. The goal is to reduce dependence on oil and limit carbon dioxide emissions (greenhouse gas). In order for these biofuels to be considered as viable alternatives to conventional fuels, it is essential to have a very detailed knowledge of their combustion kinetics. In-depth studies of overall reactivity and detailed oxidation, and in particular the nature of the pollutants formed, are therefore necessary.
Among these biofuels, alcohols are among the most promising ones, ethanol being already introduced in gasoline for example. Our previous studies [1-5] in jet-stirred reactor and shock-tube demonstrated the major role of aldehydes and ketones as key intermediates in the oxidation of alcohols. These results have highlighted the complexity of their sub-mechanisms which need to be investigated in depth to better reproduce the combustion of alcohols.
In this thesis, we will study the pyrolysis and the oxidation kinetics of a selection of aldehydes and ketones from two aspects: (i) experimental studies and (ii) kinetic modeling. The experimental aspects will include a part which will be realized in ICARE using a jet-stirred reactor, in order to obtain detailed data such as the molar fractions of the products formed during pyrolysis as a function of temperature. This study will complement the results already obtained at ICARE on the oxidation of several aldehydes and ketones. The second experimental part will be realized in DRIVE using a shock tube in order to measure auto-ignition delays under temperature and pressure conditions close to engine operation. A detailed kinetic mechanism will be developed during this thesis to represent these results. This mechanism will be integrated to the mechanisms developed in ICARE.
Even if some studies exist in the literature on the pyrolysis and oxidation of aldehydes and ketones, more data are required to assess the validity of the mechanisms involved in alcohols combustion over a wide range of operating conditions. There is a lack of experimental data and there are gaps in the understanding of the kinetics. With this thesis, we will carry out a systematic study on selected aldehydes and ketones in order to better characterize these families of molecules. Experimental results obtained in this study will be a first in the literature, as well as the kinetic mechanism. This project contributes to environmental protection since the fuels considered should help reduce both fossil fuel dependence and CO2 emissions while encouraging technological innovation.
The candidate will be required to develop a matrix of experimental data to be used as validation targets, and to synthesize and write scientific reports or articles on the results obtained.
The candidate must have solid knowledge of chemical kinetics, combustion (hydrocarbons/biofuels), and thermodynamics. The candidate must conduct experimental measurements, ensure safety, and demonstrate scientific rigor.

Contexte de travail

At the CNRS, in the ICARE UPR3021 laboratory located on the CNRS campus in Orléans, the candidate will join the OH (Hydrocarbon Oxidation) team.
ICARE is a CNRS unit attached to the Engineering Department, whose main research topics are Combustion and Reactive Systems, the Atmosphere and the Environment, as well as Space Propulsion and Atmospheric Reentry. The laboratory is composed of 8 researchers, 15 teacher-researchers, 15 ITA staff, and around 30 doctoral and postdoctoral students.
The position is in a sector subject to the protection of scientific and technical potential (PPST) and therefore, in accordance with regulations, requires your arrival to be authorized by the competent authority of the MESR.

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.