The catalytic hydrogenation of CO2 into e-fuels is considered to decarbonize certain modes of transport that are difficult to electrify. However, some of the considered reactions are thermodynamically balanced (limited CO2 conversion efficiencies) and catalyst degradation by the produced water is observed. The use of membrane reactors, allowing water separation, is envisaged. For this, the development of water-permselective membranes, without defects and resistant to synthesis conditions, is necessary. Previous studies have targeted LTA and SOD zeolite membranes for this application. However, the presence of defects reduces their selectivity, and their performance deteriorates during operation. The objective of this thesis is therefore to study the sealing of membrane defects and the deposition of protective layers on their surface to improve their performance and durability. To achieve this, the deposition of permselective zeolite layers will first be carried out hydrothermally on suitable porous supports. The sealing of defects by impregnation/conversion of silica precursors in a supercritical CO2 environment will then be studied. Finally, different protective layers (zeolite, ceramic oxide, etc.) will be deposited on the membranes (sol-gel, supercritical CO2, hydrothermal methods). The coatings will be characterized (XRD, SEM, porosimetry, elipsometry, etc.) to ensure their chemical nature, thickness/homogeneity, and porosity. Gas permeation performance will be evaluated at the various stages of preparation, and the durability of the membranes will be studied in the presence of water vapor at different temperatures.
The candidate will work within the Supercritical Processes and Decontamination Laboratory (Marcoule), and will benefit from the laboratory's expertise in ceramic membranes. The student will interact with the laboratory's technicians, engineers, doctoral students and post-doctoral fellows and will exchange with the collaborators of the Reactors and Processes Laboratory (Grenoble). The doctoral student will be involved in the different stages of the project, the publication of results and the presentation of their work at conferences. They will develop solid scientific knowledge in the fields of environment and energy, as well as in project management.