Direct insight on the zeolite steaming process at the atomic scale – in-situ TEM study of the structural and chemical changes in biomass conversion acid catalysts

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Zeolites are employed as acidic catalysts in refining, petrochemistry, pollution abatement, and biomass. These microporous materials are crystalline structures built from corner-connected SiO4 and AlO4 tetrahedra. The enhancement of the acidic properties of zeolites by specific chemical and thermal treatments proceeds through structural and chemical changes at both volume and surface scales of the mineral. The thermal treatment in the presence of water vapor, called "steaming", leads to the hydrolysis of Si-(OH)-Al bonds and generates extraframework aluminum (EFAL) species, in turn increasing acidity and porosity. The characterization of the full complexity of zeolite acidity and its modifications induced by steaming is very critical for catalytic applications, as well as technically extremely challenging. Environmental Transmission Electron Microscopy (TEM) is taylored for this challenge.
The main objectives of this thesis are: (1) to develop specific in-situ TEM methodologies for the direct observation, in real time, of the structural, chemical and textural modifications of the zeolites during the steaming processes, (2) to correlate the evolution of the acidic properties of zeolites to the structural changes observed by TEM, (3) to propose a phenomenological model allowing to account for the steaming process at the atomic scale.
The PhD will be held mostly in IPCMS lab in Strasbourg (CNRS, Université de Strabourg) under the supervision of Professor Ovidiu Ersen. IPCMS hosts a state of the art setup for TEM environmental experiments (including atmospheric pressure gas holder, liquid and electrochemical holder, mass spectrometer for the quantification of the reaction products, set-up for introducing water vapors) together with a long lasting experience in electron tomography. The supervision at IFPEN will be made by Christophe Bouchy (Catalysis division) and Virgile Rouchon (Physics and Analysis Division). The PhD will be integrated in the Joint Laboratory CARMEN, which is composed of researchers form CRMN (Lyon), PHENIX (Paris), IPCMS (Strasbourg) and IFPEN (Lyon).

Keywords: Zeolite, transmission electron microscopy, acid catalysis, porosity

  • Academic supervisor    Professor Ovidiu ERSEN, IPCMS, CNRS-Université de Strasbourg. ovidiu.ersen@ipcms.unistra.fr
  • Doctoral School    182 - Ecole Doctorale de Physique et Chimie-Physique, Université de Strasbourg
  • IFPEN supervisor    Virgile ROUCHON, IFPEN, Physics and Catalysis division. virgile.rouchon@ifpen.fr
  • PhD location    IPCMS, Strasbourg, France. 
  • Duration and start date    3 years, starting not earlier than September 2020
  • Employer    IFPEN, Solaize, France
  • Academic requirements    University Master degree in Physics or Material Sciences
  • Language requirements    Willingness to learn French
     
Contact
Encadrant IFPEN 
Virgile ROUCHON
Texte libre

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.