Elucidating the role of phosphorous on zeolites acidity and on their catalytic performances in ethanol dehydration

Producing decarbonized Jet fuel has received increasing interest lately. Using ethanol produced by biomass fermentation or from plastic wastes transformation as a platform molecule to produce ethylene is the first step to produce sustainable aviation fuels. Ethanol dehydration processes need catalysts with hydrothermal and coking resistance. MFI-type zeolites doped with phosphorous and steamed have proven to be good candidates. Adding phosphorous and hydrothermally treating the ZSM-5 modifies its textural and acidic properties, leading to more selective and stable catalysts. However, the role played by the phosphorous species formed, their evolution during the dehydration (high water partial pressure, presence of polymeric carbon species) is still unclear. Controlling the proportion of each species, their location, their stability is key to produce long lived and efficient catalysts. The objective of the PhD work will thus be to understand the role of phosphorus to improve the performance of the catalysts. The project will consist in synthesizing a variety of P-doped ZSM-5 by different methods, characterizing them by standard and advanced techniques (FT-IR, Operando-IR, 31P, 27Al, 1H NMR, XRD, N2 adsorption) and evaluating their catalytic properties on an High through put experimentation pilot unit. Correlations will be drawn between the different properties to understand which species is key for high activity, selectivity and stability to produce pure ethylene. DFT calculations (density functional theory) will aim at predicting the interactions between phosphorous and the zeolite acid sites as well as external surface models. Other less studied zeolitic (aluminosilicate) structures will be P-treated with the optimum protocol previously determined for ZSM-5. The methodology developed to characterize the P-ZSM-5 zeolites will be applied to these new solids and compared to commercial SAPO (silicoaluminophosphates) solids. Finally, mechanistic studies will be driven on HTE pilot unit to understand the role of different P species in the improved catalytic performance: steric, zeolite acidity neutralization or new acid sites formed with P involved.

Mots clefs: Ethanol dehydratation, zeolites, bioethylene, reaction mechanism, phosphorous, DFT

• Academic supervisor    Dr Céline CHIZALLET, IFPEN, https://orcid.org/0000-0001-5140-8397 
• Doctoral School    ED 206 Chimie, procédés environnement, ENS Lyon
• IFPEN supervisor    Dr Sylvie MAURY, Researcher, https://orcid.org/0000-0002-7742-8385
• PhD location    IFPEN, Solaize (69) and CP2M, Villeurbanne (69), near Lyon, France  
• Duration and start date    3 years, starting November 2025
• Employer    IFPEN, Solaize, France
• Funding    IFPEN
• Academic requirements    University Master degree in relevant disciplines: chemical sciences, materials, chemical engineering  
• Language requirements    Fluency in French or English (B2)
• Other requirements    Good computing skills (excel, word, PowerPoint at minima), good writing qualities appreciated

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