Synthesis of biosourced alkanes from fatty acid methyl ester
Alkanes or hydrocarbons are essential molecules in the energy sector (fuels) as well as in specialty chemistry (cosmetics, adhesives, etc.) and fine chemistry. Today, they are primarily derived from non-renewable fossil resources that are not available at the national scale and contribute to climate change. To reduce the carbon footprint and enhance energy independence, the efficient production of hydrocarbons from renewable and available sources such as biomass is an attractive alternative.
This thesis project focuses on developing innovative methods to produce bio-based hydrocarbons from fatty acid methyl ester (FAME). The primary objective is to extrude carbon dioxide from FAME in a single catalytic step, using light as a renewable energy source. The project is structured into two parts: the first aims to verify the compatibility of catalytic systems for breaking the C–O bond with photocatalytic decarboxylation processes, while the second focuses on recombining alkyl residues to synthesize hydrocarbons.
By contributing to reducing dependence on fossil fuels and lowering greenhouse gas emissions, the thesis project aligns with the strategy of diversifying energy sources.
Alternatives to perfluorinated compounds for water-repellent and oil-repellent treatments of textiles used for NRBC personal body protection
Finding alternatives to fluorinated compounds (PFAS) involves very diverse application areas. Among them, the treatment of technical textiles to make them water- and oil-repellent is a major challenge for manufacturing protective clothing against both aqueous and oily contaminants. Our laboratory is developing such alternatives by covalently grafting molecules onto fibers selected from those already used for technical textiles. The thesis will focus on experimental work with two components. The first component will consist of improving and qualifying, at a semi-industrial level, the water- and oil-repellent properties already obtained and qualified according to current standards (water and oil droplet sliding, slow impregnation of oil droplets) using our nanometric chemical coatings. The second component will be dedicated to optimizing the weave structure, in conjunction with the chemical treatment, to determine the optimal weave based on the desired properties. The work will be carried out in close contact with a technical textile manufacturer and with ENSAIT in Roubaix.
Development of highly reactive bio-based polyhydroxyurethanes for the substitution of isocyanates in polyurethanes
Polyurethanes are thermosetting materials with significant environmental impacts. They are primarily synthesized from isocyanates, which are highly hazardous substances (toxic, sensitizing, and some even classified as CMR - Carcinogenic, Mutagenic, or Reprotoxic) and are subject to REACH restrictions. In this context, polyhydroxyurethanes (PHUs) offer several advantages: (i) they are more easily bio-based compared to conventional PUs, (ii) their synthesis does not involve isocyanates, but (iii) instead allows for CO2 sequestration. However, the precursors used in the synthesis of PHUs (cyclic carbonates and amines) exhibit much lower reactivity than isocyanates, resulting in curing times that are currently incompatible with the temperatures and production rates required for this type of material.
Several research directions have been proposed to optimize PHU curing kinetics, focusing on the identification of (i) new cyclic carbonate and amine precursors chemically substituted at the a or ß positions of the reactive group, and (ii) new high-performance catalysts capable of activating both types of precursors used in synthesis.
In this context, the PhD candidate will be tasked with synthesizing new cyclic carbonate and amine precursors and studying their reactivity to identify the most favorable conditions for the synthesis of highly reactive PHUs. The results obtained during this work will then be analyzed using symbolic Artificial Intelligence models developed at CEA.
This PhD project is part of the PHURIOUS project, funded by the PEPR DIADEM program, which aims to integrate high-throughput synthesis and characterization techniques in polymer chemistry with digital tools, including DFT calculations, molecular dynamics simulations AI approaches.
Impact of a sodium nitrate saline plume on the radionuclide confinement properties of cementitious matrices
Using modelling to predict the migration of radioactive species through a well-known porous matrix, such as concrete, is a major challenge for society, particularly in the context of studies linked to the radioactive waste management. Demonstrating that the proposed model is robust through targeted laboratory experiments under extreme chemico-physical conditions is one of the scientific challenges proposed by the CEA as part of this PhD research project.
The young reseacher will be responsible for designing, carrying out and modelling experimental lab-tests on the retention and diffusion of radionuclides of interest in controlled cementitious conditions or under perturbation due to the nitrate plume leading to very high concentrations in the pore solution. The main expected result is to propose a predictive model coupling chemistry under extreme ionic strenght conditions and transport through complex cementitious matrices, validated by experimental data acquired on simple systems.
Surrounded by a team of experts in the field of measuring and modelling radionuclides migration in porous media, the PhD student will be able to develop or extend his/her skills in the following areas: chemistry, analytical chemistry, physico-chemistry, radiochemistry and modelling.
Functionalized aluminosilicate nanotubes for photocatalysis
Rising energy demand and the need to reduce the use of fossil fuels to limit global warming have created an urgent need for clean energy collection technologies. One interesting solution is to use solar energy to produce fuels. Low-cost materials such as semiconductors have been the focus of numerous studies for photocatalytic reactions. Among them, 1D nanostructures are promising because of their interesting properties (high and accessible specific surface areas, confined environments, long-distance electron transport and facilitated charge separation). Imogolite, a natural hollow nanotubes clay, belongs to this category. Its particularity does not lies in its chemical composition (Al, O and Si) but in its intrinsic curvature, which induces a permanent polarization of the wall, effectively separating photo-induced charges. Several modifications of these materials are possible (coupling with metal nanoparticles, functionalization of the internal cavity), enabling their properties to be modulated.We have demonstrated that this clay is a nanoreactor for photocatalytic reactions (H2 production and CO2 reduction) under UV illumination. In order to obtain a useful photocatalyst, it is necessary to extend photon collection into the visible range. One strategy considered is to encapsulate and covalently graft dyes acting as antennae in the cavity. The aim of this thesis is to synthesize imogolites with different internal functionalizations, to study the encapsulation and grafting of dyes into the cavity of these functionalized imogolites, and finally to study the photocatalytic properties.
Thermally conductive yet electrically insulating polymer nanocomposite based on core-shell (nano)fillers oriented by magnetic field
Advances in power electronics, electric motors and batteries, for example, are leading to a significant increase in heat production during operation. This increase in power density combined with reduced heat exchange surfaces amplifies the challenges associated with heat dissipation. The absence of adequate dissipation leads to overheating of electronic components, impacting on their performance, durability and reliability. It is therefore essential to develop a new generation of heat dissipating materials incorporating a structure dedicated to this structure.
The objective and innovation of the PhD student's work will lie in the use of highly thermally conductive (nano)fillers that can be oriented in an epoxy resin in a magnetic field. The first area of work will therefore be to electrically isolate the thermally conductive (nano)charges with a high form factor (1D and 2D). The electrical insulation of these charges of interest will be achieved by a sol-gel process. The synthesis will be controlled and optimised with a view to correlating the homogeneity and thickness of the coating with the dielectric and thermal performance of the (nano)composite. The second part will focus on the grafting of magnetic nanoparticles (NPM) onto thermally conductive (nano)fillers. Commercial NPMs will be evaluated as well as grades synthesised in the laboratory. The (nano)composites must have a rheology compatible with the resin infusion process.
Modeling and experimental validation of a catalytic reactor and optimization of the process for the production of e-Biofuels
During the past 20 years, « Biomass-to-liquid » processes have considerably grown. They aim at producing a large range of fuels (gasoline, kerozene, diesel, marine diesel oil) by coupling a biomass gazéification into syngaz unit (CO+CO2+H2 mixture) and a Fischer-Tropsch (FT) synthesis unit. Many demonstration pilots have been operated within Europe. Nevertheless, the low H/C ratio of bio-based syngaz from gasification requires the recycling of a huge quantity of CO2 at the inlet of gaseification process, which implies complex separation and has a negative impact on the overall valorization of biobased carbon. Moreover, the possibility to realize, in the same reactor, the Reverse Water Gas Shift (RWGS) and Fischer-Tropsch (FT) reaction in the same reactor with promoted iron supported catalysts has been proved (Riedel et al. 1999) and validated in the frame of a CEA project (Panzone, 2019).
Therefore, this concept coupled with the production of hydrogen from renewable electricity opens new opportunities to better valorize the carbon content of biomass.
The PhD is based on the coupled RWGS+FT synthesis in the same catalytic reactor. On the one hand a kinetic model will be developed and implemented in a multi-scale reactor model together with hydrodynamic and thermal phenomena. The model will be validated against experimental data and innovative design will be proposed and simulated. On the other hand, the overall PBtL process will be optimized in order to assess the potential of such a process.
Brines for metal recycling
Critical metals are essential for a range of technologies that are vital to reduce our carbon dioxide emissions. However, the global recycling rate for metals contained in electronic waste is below 20%, indicating that electronic waste is a relatively untapped source of metals. Additionally, it is increasingly urgent to develop effective processes for recycling waste from products like solar panels, as the volume of waste solar pannels generated is set to rise significantly in the coming years. Currently, conventional hydrometallurgical methods often rely on toxic aqueous solutions to dissolve metals, which presents substantial environmental challenges.
This project proposes an innovative alternative by using concentrated brines (aqueous salt solutions) to oxidize and dissolve metals. This thesis will investigate the fundamental properties of brines and their ability to dissolve metals through various techniques, particularly electrochemical methods. Artificial intelligence methods developed within the lab will be employed to screen a wide range of brines that would allow metal dissolution. Subsequently, brine-based recycling processes will be developed to recover metals from printed circuit boards and solar panels. Finally, metal separation and the treatment of used brines will be explored using membrane and electrochemical processes.