In order to reduce the energy consumption of catalytic processes, one of the levers is to optimize catalysts. This optimization is accompanied by an ever-increasing need to characterize these solids. This is particularly the case for hydrotreating catalysts that produce fuels and chemical intermediates with low environmental impact. The preparation of these catalysts is composed of a series of unit steps that will make it possible to design the future properties of the solid: from impregnation on the alumina support of metal species based on molybdenum heteropolyanions to activation in a sulfo-reducing medium to obtain the active phase, through maturation and drying. These steps of impregnation and maturation of the oxide catalysts are undergone and lead to a heterogeneous distribution of species on the support that can have a negative impact on the catalytic activity. However, the identification and quantification of these species remain a major challenge. To meet this challenge, we propose to use and optimize a spatially resolved X-ray absorption chemical imaging technique on the Quick-XAS ROCK beamline of the SOLEIL synchrotron. After the spatial and temporal optimization of the XAS analysis by chemical imaging on a catalyst impregnated with a molybdenum-based heteropolyanion solution, the PhD student will have to develop a methodology to monitor impregnation and maturation within the support. He will have to identify and quantify by XAS and Raman the different molybdenum-based compounds according to the nature of the solution and their evolution during the maturation stage. In situ monitoring of the activation step in a sulfide environment will also be studied in order to describe the activation mechanism of previously identified and localized species, in order to determine the ones most likely to generate active phases.
Keywords: Chemical imaging, spatial resolution, X-Ray Absorption, quantification, oxide catalysts
- Academic supervisor Dr BRIOIS Valérie, Directeur de recherche au CNRS (DR1), responsible of the ROCK beamline of SOLEIL synchrotron
- Doctoral School 571 - Ecole Doctorale Chimie de Paris-Sud
- IFPEN supervisor Dr LEGENS Christèle, Materials characterization department, firstname.lastname@example.org
- PhD location Synchrotron SOLEIL, St Aubin, France (3/4) and IFP Energies nouvelles, Lyon, France (1/4)
- Duration and start date 3 years, starting not earlier than September 2020
- Employer IFP Energies nouvelles, Lyon, France
- Academic requirements University Master degree in relevant disciplines
- Language requirements Fluency in French and/or English, willingness to learn French
IFP Energies nouvelles is a French public-sector research, innovation and training center. Its mission is to develop efficient, economical, clean and sustainable technologies in the fields of energy, transport and the environment. For more information, see https://www.ifpen.com.
IFPEN offers a stimulating research environment, with access to first in class laboratory infrastructures and computing facilities. IFPEN offers competitive salary and benefits packages. All PhD students have access to dedicated seminars and training sessions.