Description du sujet de thèse

The objective of this CNRS doctoral position is to explore the demethylation of lignins assisted by high-frequency ultrasound (i.e., generation of cavitation bubbles). The demethylation of lignin fragments or lignins is an important reaction that allows access to polyphenolic derivatives, a family of compounds widely used for the production of a wide range of chemicals (antioxidants, materials, etc.). In terms of methodology, and based on preliminary results obtained by the host laboratory, the reactions will first be studied on model compounds of the "anisole" type, such as anisole, syringol, guaiacol, and then applied to lignin models and technical lignins to (1) compare this approach with more traditional pathways (acid catalysis, enzymatic) in terms of performance and (2) evaluate the impact of this ultrasonic activation on other bonds in the lignins (i.e., selectivity in terms of depolymerization/repolymerization of lignins). Energy consumption, selectivity, and reactor productivity are essential criteria that will be considered to assess the economic and environmental feasibility of this research work. The reactions will typically be performed in a high-frequency ultrasound reactor (550 kHz), and the reaction will be monitored by gas and liquid chromatography as well as by 1H/13C NMR and mass spectrometry.
This CNRS doctoral position is part of a larger project funded by France 2030 (PEPR B-BEST). The candidate will therefore be required to collaborate with other laboratories within the consortium.
Holding a Master's degree (or equivalent), the candidate must have solid knowledge in the field of catalysis (homogeneous or heterogeneous) applied to organic chemistry. The candidate should also be curious and imaginative, able to challenge the team by proposing, for example, radically different approaches.
The position is located in a sector related to the protection of scientific and technical potential (PPST) and therefore requires, in accordance with regulations, that your arrival be authorized by the competent authority of the MESR.

Contexte de travail

This research will be conducted at the CNRS at the Institute of Chemistry of Poitiers (IC2MP), located at the University of Poitiers in France. IC2MP is a joint unit between the University of Poitiers and CNRS working on the design of sustainable reactions/products. It is an interdisciplinary institute that studies (1) the design of clean processes (catalysis, bio-solvents, renewable energy, alternative technologies, etc.) and (2) the transfer and bioaccumulation of organic molecules in ecosystems. In this project, the candidate will join the "Catalysis in Unconventional Media" team. The team conducts research on (1) replacing fossil carbon with renewable carbon and (2) developing clean technologies for chemistry. The candidate will have full access to the IC2MP analytical platform (PLATINA), which includes all the major equipment required to characterize organic molecules and catalysts generated in the course of this project (XPS, XRD, TEM/SEM, mass spectrometry, NMR, etc.). The recruited CNRS doctoral researcher will be under the responsibility of a CNRS research director.

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.

Contraintes et risques

Possible travels in France and/or abroad. Standard chemical risk.