Modeling of active phase - support interactions during impregnation and drying processes: towards a better understanding of catalytic activity

The control of the textural properties of alumina supports is a crucial issue in the manufacturing of novel catalytic materials. Indeed, mass transport inside the porous medium is strongly affected by the micro-structure and may decrease the impregnation efficiency of the active phase leading to a loss of catalytic activity. Alumina carriers are constituted of elementary crystals (of a few Å) formed during the precipitation step, that stick together to form aggregates (of a few nm). These clusters can become intertwined to form agglomerates (of 100 nm to 1 µm). The resulting assembly constitutes the complex porous network which combines different spatial scales and leads to a wide distribution of pore diameters. The catalyst manufacturing procedure consists in a succession of several unitary operations starting from a boehmite powder to a shaped alumina carrier that is subsequently impregnated with an active phase. The catalyst performance results from all those operations.
Today, no obvious link has yet been made between the textural properties of a carrier, the properties of the impregnation solution and the different operating conditions used in each unitary operation on the final activity of a catalyst. The objective of this Ph.D. thesis is to model the impregnation and drying steps during the deposition of the active phase in a porous alumina carrier. The location of the crystals, their dispersion and their size will control the final performance of the catalyst. The description of this step will make it possible to predict these three characteristics and thus identify relevant descriptors of the catalyst performance by comparing the model to catalytic tests performed with a model reaction. The prediction of properties such as pore size distribution, connectivity, and crystal size, will help us to propose innovations on the porous structure of the carrier, on the impregnation solution and on the operating conditions.

Keywords: Catalyst Impregnation, Pore Network Model, Coupled Diffusion-Reaction Equations

• Academic supervisor    Dr. SCHWEITZER Jean-Marc, Reaction and Reactor Modeling Department, jean-marc.schweitzer@ifpen.fr.
• Doctoral School    ED206, Ecole Doctorale de Chimie de Lyon, https://www.edchimie-lyon.fr/
• IFPEN supervisor    Dr. VERSTRAETE Jan, Reaction and Reactor Modeling Department, jan.verstraete@ifpen.fr, ORCID 0000-0003-4536-5639.
• PhD location    IFP Energies nouvelles, Lyon, France
• Duration and start date    3 years, starting in fourth quarter 2023
• Employer    IFP Energies nouvelles, Lyon, France
• Academic requirements    University Master’s degree in Chemical Engineering
• Language requirements    Fluency in French or English, willingness to learn French
• Other requirements    Programming knowledge required

To apply, please send your cover letter and CV to the IFPEN supervisor indicated here above.